Vanilla Custard Sponge Cake (Genoise with Caramel and Custard Soak)
Vanilla Custard Sponge Cake (Genoise with Caramel and Custard Soak) is a hard French recipe that serves 8. 512 calories per serving. Recipe by Claire Saffitz x Dessert Person on YouTube.
Prep: 1 hr 11 min | Cook: 2 hrs 25 min | Total: 4 hrs 6 min
Cost: $9.26 total, $1.16 per serving
Ingredients
- 6 large eggs (whole, room temperature)
- 188 g granulated sugar (for sponge)
- 150 g all‑purpose flour (sifted twice)
- 40 g unsalted butter (melted and cooled)
- 1 pinch salt
- 2 tsp vanilla extract (Heilala paste or extract) (or more to taste)
- 150 g granulated sugar (for caramel) (dry caramel, no water)
- 2 cup heavy cream (full‑fat)
- 2 cup whole milk
- 100 g Demerara sugar (half cup, coarse)
- 1/2 bean vanilla bean (split lengthwise, seeds scraped)
- 6 egg yolks (room temperature)
- 2 whole eggs (for custard) (room temperature)
Instructions
Preheat Oven & Prepare Pan
Preheat the oven to 350°F. Line the bottom of a 9‑inch high‑sided cake pan with parchment paper (do not grease).
Time: PT5M
Temperature: 350°F
Warm Egg‑Sugar Mixture
Place 6 whole eggs, 188 g granulated sugar, and a pinch of salt in a large glass bowl. Set the bowl over a pot of gently steaming water (no boil). Whisk constantly until the mixture reaches 113°F.
Time: PT5M
Whip the Egg Foam
Transfer the warmed mixture to the stand mixer. Start on medium speed, then increase to high, whipping until the volume has quadrupled, the mixture is thick, light, and forms a ribbon when the whisk is lifted.
Time: PT5M
Add Vanilla
Quickly whisk in 2 tsp vanilla extract (or Heilala vanilla paste).
Time: PT1M
Fold in Flour
Sift one‑third of the 150 g flour over the foam and gently fold with the skimmer. Repeat with the second third, then the final third, working quickly to avoid deflating the foam.
Time: PT5M
Incorporate Butter
Stream the 40 g melted, cooled butter into the batter while folding with the skimmer until fully incorporated.
Time: PT2M
Transfer to Pan & Smooth
Using a rubber spatula, scrape the batter into the prepared pan, smoothing the top. Tap the pan on the counter to pop any large air bubbles.
Time: PT2M
Bake the Genoise
Bake at 350°F for 20–25 minutes, until the surface is golden‑brown, the cake springs back when touched, and a tester comes out clean.
Time: PT25M
Temperature: 350°F
Make Dry Caramel
While the sponge bakes, melt 150 g granulated sugar in a saucepan over medium heat, adding it in thin layers and stirring only when needed, until it turns a deep amber color.
Time: PT7M
Coat Pan with Caramel
Immediately pour the hot caramel into the bottom of the same cake pan, swirling to coat the entire surface. Set aside to cool and harden.
Time: PT5M
Heat Milk & Cream with Vanilla Bean
Combine 2 cup heavy cream, 2 cup whole milk, a pinch of salt, and the split vanilla bean (seeds scraped in) in the saucepan. Warm over medium heat until just steaming (no boil).
Time: PT5M
Whisk Egg‑Sugar Custard Base
In a separate bowl, whisk together 6 egg yolks, 2 whole eggs, and 100 g Demerara sugar until thick and slightly foamy.
Time: PT2M
Temper the Egg Mixture
Slowly stream the warm milk‑cream mixture into the egg‑sugar bowl while whisking constantly, raising the temperature of the eggs without cooking them. Once incorporated, whisk the entire custard briefly.
Time: PT3M
Cool Sponge & Unmold
Remove the baked sponge from the oven and let it cool upside‑down on a rack. Once cool, run an offset spatula around the sides, then invert onto parchment and gently lift out of the pan.
Time: PT10M
Level the Sponge
Using a serrated knife, trim the top and bottom of the sponge to create two flat surfaces. The smoother side will later sit against the caramel.
Time: PT10M
Assemble Cake Base
Place the caramel‑coated pan on the work surface. Lay the trimmed sponge, smoother side down, onto the caramel. Press gently to adhere.
Time: PT2M
Poke Holes
Using a metal skewer (or thick toothpick), poke a dense grid of holes through the sponge down to the caramel layer.
Time: PT5M
Strain Custard Over Cake
Place a fine strainer over the assembled cake and slowly pour the warm custard through, allowing it to fill the holes and soak the sponge.
Time: PT2M
Rest & Absorb
Cover the cake loosely with foil and refrigerate for at least 4 hours, preferably overnight, to let the sponge fully absorb the custard.
Time: PT4H
Prepare Water Bath
Place the cake pan inside a larger roasting pan. Fill the outer pan with boiling water until it reaches halfway up the sides of the cake pan.
Time: PT5M
Bake Custard Cake
Cover the cake pan with foil. Bake in a 325°F oven, water‑bathing the cake, for about 1 hour 45 minutes, or until an instant‑read thermometer inserted into the center reads 170°F.
Time: PT1H45M
Temperature: 325°F
Cool & Chill
Remove the cake from the water bath, discard the foil, and let it cool to room temperature. Then refrigerate for at least 2 hours before unmolding.
Time: PT2H
Unmold and Serve
Run an offset spatula around the sides, invert the cake onto a serving plate, and slice with a sharp knife. Serve chilled.
Time: PT5M
Nutrition Facts
- Calories
- 512
- Protein
- 12 g
- Carbohydrates
- 68 g
- Fat
- 24 g
- Fiber
- 0 g
Dietary info: vegetarian, contains gluten
Allergens: eggs, milk, wheat
Ingredient Substitutions
- Instead of granulated sugar (for sponge): caster sugar
- Instead of all‑purpose flour: cake flour
- Instead of unsalted butter: margarine
- Instead of vanilla extract (Heilala paste or extract): vanilla bean seeds
- Instead of granulated sugar (for caramel): light brown sugar
- Instead of heavy cream: half‑and‑half
- Instead of whole milk: 2% milk
- Instead of Demerara sugar: light brown sugar
- Instead of vanilla bean: vanilla paste
Equipment Needed
- stand mixer with whisk attachment
- large glass mixing bowl
- double boiler or saucepan with steaming water
- instant‑read thermometer
- fine‑mesh sieve
- spatula (rubber)
- skimmer/folding spatula
- 9‑inch high‑sided cake pan
- parchment paper
- cooling rack (optional)
- knife (serrated) and offset spatula
- metal skewer or toothpick (optional)
- roasting pan for water bath
- aluminum foil
- strainer (optional)
Critical Steps — Do Not Skip
- Warming the egg‑sugar mixture to 113°F without cooking the eggs
- Folding the flour gently to preserve the airy foam
- Making a dry caramel without water to avoid crystallization
- Tempering the custard mixture to prevent curdling
- Baking the assembled cake in a water bath until the center reaches 170°F
Chef Tips from the Video
- Use high‑quality vanilla (Heilala) for the most aromatic result.
- A glass bowl slows heating, giving you better control over the egg foam temperature.
- If you don’t have a stand mixer, a hand‑held electric whisk on the highest setting can work, but expect longer whipping time.
- For an even mirror finish on the top, place a light weight (e.g., a foil‑wrapped pan) on the cake during the final hour of baking.
Troubleshooting
Sponge collapsed after baking
Make sure the egg‑sugar mixture is fully aerated and not over‑folded. Avoid greasing the pan sides.
Custard is runny after baking
Check the internal temperature; it must reach 170°F. If under‑baked, continue baking in 5‑minute increments.
Caramel hardened before coating the pan
Re‑heat the pan in a 325°F oven for a few minutes or gently re‑melt the caramel over low heat.
Cake is too dry
Ensure the custard is warm when poured and that the sponge was fully leveled to maximize absorption.
Storage
Refrigerator: Store sealed in an airtight container for up to 4 days.
Freezer: Can freeze for up to 1 month; thaw in the refrigerator before serving.
Room temperature: Not recommended due to dairy and egg content.
Make-Ahead Tips
- Bake the genoise a day ahead and store wrapped at room temperature.
- Prepare the dry caramel and let it harden; re‑heat briefly before use.
- Custard can be made up to 24 hours in advance and kept refrigerated.
Frequently Asked Questions
What is the cultural significance and history of Vanilla Custard Sponge Cake (Genoise with Caramel and Custard Soak) in French pastry tradition?
Vanilla Custard Sponge Cake (Genoise with Caramel and Custard Soak) blends the classic French genoise sponge with elements of flan and tres leches, reflecting France's love for airy cakes and rich custards. Historically, the genoise was created in the 19th century and later inspired layered desserts that showcase technique and elegance. This modern hybrid honors that legacy while introducing a caramel-soaked custard center that feels contemporary yet rooted in French patisserie.
What are the traditional regional variations of Vanilla Custard Sponge Cake (Genoise with Caramel and Custard Soak) in France?
In northern France, genoise‑based cakes often incorporate butter and almond flour, while southern regions favor a lighter, oil‑based sponge with citrus zest. Some Provençal versions replace the caramel base with orange marmalade, and in Brittany, a touch of salted butter caramel is added to echo local salted butter traditions. These regional tweaks illustrate how the core concept can be adapted to local tastes while preserving the cake’s airy texture.
How is Vanilla Custard Sponge Cake (Genoise with Caramel and Custard Soak) authentically served in French cafés or patisseries?
French pâtisseries typically present this cake as a single‑slice portion on a fine porcelain plate, dusted lightly with powdered sugar and accompanied by a dollop of fresh whipped cream or a quenelle of vanilla ice cream. A thin drizzle of caramel and a garnish of edible gold leaf or fresh berries add visual elegance. Service is often accompanied by a café au lait to balance the richness of the custard soak.
On what French occasions or celebrations is Vanilla Custard Sponge Cake (Genoise with Caramel and Custard Soak) traditionally associated?
While not tied to a specific holiday, this luxurious cake is popular for celebratory events such as birthdays, bridal showers, and fêtes de la musique, where a show‑stopping dessert is prized. Its elegant presentation makes it a favored choice for high‑tea gatherings and upscale dinner parties throughout France. The custard soak also aligns with the French tradition of offering a “dessert de fête” that feels indulgent yet refined.
How does Vanilla Custard Sponge Cake (Genoise with Caramel and Custard Soak) fit into the broader French cuisine tradition of layered cakes and custards?
French cuisine celebrates layered pastries like mille‑feuille and opera cake, which combine crisp layers with creamy fillings. This vanilla custard sponge cake continues that tradition by pairing a delicate genoise with a silky baked custard and a thin caramel sheet, echoing the textural contrasts prized in classic French desserts. Its water‑bath technique also mirrors the precision used in French custard preparations such as crème brûlée.
What are the authentic traditional ingredients for Vanilla Custard Sponge Cake (Genoise with Caramel and Custard Soak) versus acceptable modern substitutes?
Authentic ingredients include large eggs, granulated sugar, all‑purpose flour, unsalted butter, a pinch of salt, pure vanilla bean, and caramel made from white sugar and butter. Modern bakers may substitute clarified butter for the caramel, use cake flour for a softer crumb, or replace vanilla beans with high‑quality vanilla extract. However, the core structure relies on the egg‑sugar foam and butter‑enriched sponge to achieve the classic French texture.
What other French desserts pair well with Vanilla Custard Sponge Cake (Genoise with Caramel and Custard Soak) for a complete pâtisserie platter?
A crisp tarte aux pommes, a buttery madeleine, and a small serving of tarte au citron (lemon tart) complement the custard cake’s richness. Light fruit sorbets, such as raspberry or peach, provide a refreshing contrast, while a glass of chilled Sauternes or a classic French café au lait balances the sweetness. Together they create a harmonious French dessert tasting menu.
What are the most common mistakes to avoid when making Vanilla Custard Sponge Cake (Genoise with Caramel and Custard Soak) at home?
Over‑mixing the egg‑sugar foam can deflate the genoise, resulting in a dense crumb. Baking the cake without a proper water bath may cause the custard to crack or dry out. Finally, failing to score the caramel sheet before baking can lead to uneven soaking and a gummy texture.
Why does this Vanilla Custard Sponge Cake (Genoise with Caramel and Custard Soak) recipe use a water bath (bain‑marie) instead of baking it directly in the oven?
The water bath provides gentle, even heat that prevents the custard from curdling and keeps the center wobbly and silky. It also protects the delicate genoise from the dry, high heat that could dry it out, ensuring the cake remains moist and airy. This technique is a hallmark of French custard desserts like flan and crème brûlée.
How can I tell when the Vanilla Custard Sponge Cake (Genoise with Caramel and Custard Soak) is done cooking and has the desired wobbly center?
The edges should be set and lightly golden while the center gently jiggles when the pan is tapped, similar to a perfectly baked soufflé. A quick test with a thin skewer inserted near the edge should come out clean, but the middle will still feel soft. The custard will continue to set as it cools, achieving a silky wobble at room temperature.
What does the YouTube channel Claire Saffitz x Dessert Person specialize in, and how does its cooking philosophy influence the Vanilla Custard Sponge Cake (Genoise with Caramel and Custard Soak) recipe?
The YouTube channel Claire Saffitz x Dessert Person specializes in detailed, technique‑driven pastry and dessert tutorials that blend classic French methods with modern home‑cook accessibility. Their philosophy emphasizes precision, ingredient integrity, and clear visual instruction, which is evident in the meticulous steps for the genoise sponge, caramel sheet, and water‑bath custard soak in this recipe. This approach makes a traditionally challenging French cake achievable for enthusiastic bakers.
Last updated: August 21, 2026
