Chocolate Log Cake (Ulog) with Chocolate Buttercream and Meringue Mushrooms

Ingredients

• 4 pieces Large eggs (separated – yolks for batter, whites for meringue)
• 1 1/3 cups Granulated sugar (divided: 2/3 cup for yolk mixture, 2/3 cup for egg‑white meringue)
• 1 1/2 cups Cake flour (sifted twice for a tender sponge)
• 3 tablespoons Dutch‑process cocoa powder (gives deep color and less acidity)
• 1 teaspoon Baking powder
• 1/2 teaspoon Baking soda
• 1/2 teaspoon Kosher salt (divided between batter and egg‑white foam)
• 2 teaspoons Instant coffee granules (optional, adds depth to chocolate flavor)
• 1/4 cup Buttermilk (adds acidity and tenderness)
• 5 tablespoons Unsalted butter (Cary Gold) (melted, cooled slightly before adding to yolk mixture)
• 2 teaspoons Vanilla extract
• 1 cup Heavy cream (for chocolate filling and buttercream)
• 3 ounces Milk chocolate (chopped) (smoothly melts into the filling; use good quality milk chocolate)
• 1/2 cup Crème fraîche (stabilizes the chocolate filling)
• 8 ounces Dark chocolate (60% cocoa) (for chocolate buttercream; melt and cool before adding)
• 1 cup Powdered sugar (for buttercream syrup)
• 1/4 cup Water (for sugar syrup)
• 2 large Egg yolks (for buttercream)
• 2 large Whole eggs (for buttercream)
• 1/8 teaspoon Cream of tartar (stabilizes meringue)
• 1/2 cup Powdered sugar (for meringue)
• 1 teaspoon Vanilla paste
• 75 grams Egg whites (for meringue mushrooms) (about 2–3 large egg whites)

Instructions

1. Sift dry ingredients

   In a medium bowl whisk together cake flour, Dutch‑process cocoa powder, baking powder, baking soda, and kosher salt. Sift twice to avoid lumps.

   Time: PT5M

2. Prepare yolk mixture

   Separate the 4 eggs. In a large bowl whisk the 4 yolks with 2/3 cup granulated sugar until the sugar is mostly dissolved. Add instant coffee (if using), vanilla extract, melted butter, and buttermilk. Whisk until smooth.

   Time: PT5M

3. Combine wet and dry

   Add the wet yolk mixture to the dry ingredients. Whisk until the batter is smooth and free of lumps. It will be thick, similar to brownie batter.

   Time: PT3M

4. Whip egg whites

   In a clean large bowl, add the 4 egg whites, a pinch of kosher salt, and cream of tartar. Start on low speed, then increase to medium‑high. When foamy, slowly drizzle the remaining 2/3 cup granulated sugar while continuing to beat. Whip until stiff, glossy peaks form.

   Time: PT10M

5. Fold egg whites into batter

   Add about one‑third of the whipped egg whites to the chocolate batter and gently fold with an offset spatula to lighten. Then fold in the remaining whites in two additions, being careful not to over‑mix.

   Time: PT5M

6. Prepare pan and spread batter

   Grease only the bottom of the half‑sheet pan with a thin layer of butter. Lay a piece of parchment paper on the bottom (do not grease the sides). Pour the batter into the pan and spread with an offset spatula to an even 1‑inch thickness.

   Time: PT3M

7. Bake the sponge

   Place the pan in a pre‑heated 350°F (177°C) oven. Bake for 12 minutes, checking at 10 minutes. The surface should be matte and spring back when pressed.

   Time: PT12M

   Temperature: 350°F

8. Roll the hot sponge

   While the cake is still hot, dust a clean kitchen towel with a light layer of cocoa powder. Invert the cake onto the towel, peel off parchment, and gently roll the cake (with towel) into a log shape. Let it cool completely on the towel.

   Time: PT10M

9. Make chocolate filling

   In a saucepan, combine 1/2 cup heavy cream and 3 oz chopped milk chocolate. Heat over medium‑low, whisking until smooth. Remove from heat, whisk in the remaining 1/2 cup heavy cream, then add 1/2 cup crème fraîche and a pinch of salt. Chill the mixture in an ice‑water bath until firm enough to pipe.

   Time: PT5M

10. Chill filling

    Transfer the cooled filling to a bowl, cover, and refrigerate for at least 2 hours so it sets.

    Time: PT2H

11. Prepare meringue mushrooms

    In the stand mixer, whisk 75 g egg whites with a pinch of kosher salt and cream of tartar. When foamy, add 1/2 cup granulated sugar slowly, then increase speed to medium‑high until stiff peaks form. Add 1/2 cup powdered sugar and continue beating to glossy, firm peaks. Finally, fold in 1 tsp vanilla paste.

    Time: PT15M

12. Pipe mushrooms

    Fit a piping bag with a large round tip. Pipe stems (tall thin lines) onto a parchment‑lined baking sheet, then pipe caps (shorter, wider blobs) on top of each stem. Aim for about a dozen mushrooms.

    Time: PT5M

13. Bake mushrooms

    Bake the piped meringues in a 200°F (93°C) oven for 30‑35 minutes, checking after 30 minutes. They should be dry to the touch and lightly golden on the caps.

    Time: PT35M

    Temperature: 200°F

14. Make chocolate buttercream

    In a small saucepan combine 1 cup granulated sugar and 1/4 cup water. Cook over medium heat, stirring until dissolved, then bring to 238°F (115°C) without stirring. Meanwhile, in the stand mixer whisk 2 egg yolks + 2 whole eggs with a pinch of salt until foamy. Once the syrup reaches temperature, slowly pour it into the egg mixture while the mixer runs on medium‑high. Continue mixing until the bowl feels cool to the touch. With the mixer on medium, add 2 ½ sticks (1 ¼ cup) softened Cary Gold butter a few tablespoons at a time, mixing after each addition. When fully incorporated, melt and cool 8 oz dark chocolate, then add it to the buttercream along with 2 tsp vanilla extract. Whisk until glossy and smooth.

    Time: PT22M

15. Fill and re‑roll the sponge

    Unroll the cooled sponge on a clean surface. Spread the chilled chocolate‑creme fraîche filling evenly, leaving a small border. Re‑roll tightly, wrap the towel around the log, and refrigerate for at least 2 hours to set.

    Time: PT10M

16. Buttercream the log and add mushrooms

    Remove the chilled log from the towel. Using an offset spatula, coat the entire log with a thin crumb coat of chocolate buttercream. Chill 15 minutes, then apply a final smooth layer. Pipe or dollop the remaining buttercream to create bark‑like texture. Arrange the baked meringue mushrooms on the surface, adhering them with a dab of buttercream.

    Time: PT15M

17. Final trim and dust

    Trim any uneven ends with a serrated knife. Grate a little dark chocolate over the top and dust lightly with powdered sugar to mimic snow.

    Time: PT5M

18. Serve

    Allow the cake to sit at room temperature for 20 minutes before slicing. Cut into 12 even slices and serve.

    Time: PT20M

Nutrition Facts

Calories

350

Protein

5 g

Carbohydrates

45 g

Fat

18 g

Fiber

2 g