Rainbow KitKat Cake
Rainbow KitKat Cake is a medium Japanese recipe that serves 12. 350 calories per serving.
Prep: 1 hr 20 min | Cook: 35 min | Total: 2 hrs 10 min
Cost: $16.99 total, $1.42 per serving
Ingredients
- 6 bars KitKat Bars (milk chocolate, broken into small pieces)
- 200 g Unsalted Butter (softened, room temperature)
- 150 g Granulated Sugar (fine)
- 4 large Eggs (room temperature)
- 200 ml Whole Milk (fresh)
- 200 g All-Purpose Flour (sifted)
- 2 Tbsp Vegetable Oil (neutral flavor)
- 100 g Dark Chocolate (chopped for melting)
- 1 set Food Coloring (Rainbow) (gel colors for buttercream)
- 30 g Rainbow Sprinkles (for decoration)
- 1 drop Red Food Coloring (for red buttercream)
- 1 drop Blue Food Coloring (for blue buttercream)
Instructions
Prepare KitKat Chocolate Base
Shred the KitKat bars, place them in a heat‑proof bowl and melt gently over a simmering water bath or in short bursts in the microwave, stirring until smooth.
Time: PT10M
Set Chocolate Base
Pour the melted KitKat chocolate into the bottom of the cake mold, spreading evenly with a spatula. Refrigerate for 15 minutes until firm.
Time: PT15M
Make Cake Batter
In a mixing bowl whisk the eggs, then add sugar, milk, vegetable oil, sifted flour and melted dark chocolate. Mix until just combined; do not over‑mix.
Time: PT10M
Bake Cake Layers
Preheat the oven to 180°C. Divide the batter evenly over the chilled KitKat base (or into separate molds for multiple layers). Bake for 35 minutes or until a toothpick comes out clean.
Time: PT35M
Temperature: 180°C
Cool Cakes
Remove the cakes from the oven and let them cool in the mold for 10 minutes, then turn out onto a cooling rack and cool completely, about 20 minutes.
Time: PT30M
Prepare Buttercream
Beat the softened butter until fluffy, add sugar gradually, then blend in melted dark chocolate. Divide into three bowls and tint one red, one blue, and leave one natural for the outer coat using food coloring.
Time: PT10M
Assemble Cake
Place the first cake layer on a serving plate, spread a thin layer of neutral buttercream, add the next layer, repeat until all layers are stacked. Finish with a thin crumb coat of neutral buttercream and chill 10 minutes.
Time: PT15M
Cover and Smooth
Apply a final thick layer of neutral buttercream over the entire cake. Use an offset spatula to smooth the surface.
Time: PT10M
Decorate
Pipe red buttercream at the base, blue buttercream on top, and create rainbow swirls with colored buttercream. Sprinkle rainbow sprinkles, attach KitKat bars around the sides, and place the KitKat logo on top.
Time: PT15M
Set and Serve
Refrigerate the decorated cake for 10 minutes to set the decorations, then bring to room temperature before slicing and serving.
Time: PT10M
Nutrition Facts
- Calories
- 350
- Protein
- 4g
- Carbohydrates
- 45g
- Fat
- 18g
- Fiber
- 2g
Dietary info: Vegetarian, Contains gluten, Contains dairy
Allergens: Eggs, Milk, Wheat (gluten), Soy (oil)
Ingredient Substitutions
- Instead of KitKat Bars: Milkybar, Nestlé Crunch
- Instead of Unsalted Butter: Margarine (for baking)
- Instead of Granulated Sugar: Caster sugar
- Instead of Eggs: Egg replacer
- Instead of Whole Milk: Almond milk (will change flavor)
- Instead of All-Purpose Flour: Cake flour
- Instead of Vegetable Oil: Canola oil
- Instead of Dark Chocolate: Semi‑sweet chocolate
- Instead of Food Coloring (Rainbow): Natural fruit powders
- Instead of Rainbow Sprinkles: Edible glitter
Equipment Needed
- Mixing Bowl
- Whisk
- Electric Mixer (optional)
- Spatula
- Saucepan
- Baking Mold
- Oven
- Refrigerator
- Piping Bag (optional)
- Offset Spatula (optional)
- Cooling Rack (optional)
- Kitchen Scale (optional)
Critical Steps — Do Not Skip
- Melt KitKat chocolate evenly without scorching
- Do not over‑bake the cake layers
- Apply a crumb coat and chill before final frosting to avoid cracks
Chef Tips from the Video
- Sift the flour for a lighter crumb
- Use a kitchen scale for precise measurements
- For extra shine, brush the finished cake with a thin layer of melted chocolate
Troubleshooting
Cake is dense or sinks in the middle
Ensure not to over‑mix the batter and bake at the correct temperature; check oven calibration.
Buttercream cracks on the surface
Make sure the cake is completely cool and the buttercream is at room temperature; chill briefly before applying the final coat.
KitKat chocolate base becomes grainy
Melt the KitKat slowly over a bain‑marie and stir continuously; avoid high direct heat.
Storage
Refrigerator: Store in an airtight container for up to 3 days.
Freezer: Wrap tightly in plastic wrap and foil; freeze up to 1 month.
Room temperature: Can sit at room temperature for 2‑3 hours after removal from fridge.
Make-Ahead Tips
- Prepare the KitKat chocolate base a day ahead and keep refrigerated
- Buttercream can be made 2 days in advance and stored in the fridge
- Bake the cake layers and freeze them if not assembling immediately
Frequently Asked Questions
What is the cultural significance and history of Rainbow KitKat Cake in Japanese cuisine?
Rainbow KitKat Cake blends the beloved Japanese KitKat chocolate bar with Western cake techniques, reflecting Japan’s love for playful, colorful desserts that often feature popular snack brands as decorative elements.
What are the traditional regional variations of KitKat cake in Japan?
In Japan, KitKat cake variations include matcha‑flavored sponge with KitKat pieces, strawberry‑cream versions for spring, and the rainbow version that uses colorful buttercream to celebrate festivals like Children’s Day.
How is Rainbow KitKat Cake traditionally served in Japanese celebrations?
It is typically sliced into small, bite‑size pieces and served alongside tea or coffee at birthday parties, school events, and seasonal festivals where bright colors and recognizable KitKat branding add a festive touch.
What occasions or celebrations is Rainbow KitKat Cake traditionally associated with in Japanese culture?
The cake is popular for birthdays, graduation parties, and the KitKat‑themed “KitKat Day” (November 11) where fans showcase creative KitKat desserts.
What makes Rainbow KitKat Cake special or unique in Japanese dessert tradition?
It combines a recognizable confection (KitKat) as both flavor and decorative element, uses vivid rainbow buttercream that mirrors Japan’s love for kawaii (cute) aesthetics, and merges Western baking with Japanese snack culture.
What are the most common mistakes to avoid when making Rainbow KitKat Cake?
Common errors include overheating the KitKat chocolate, over‑mixing the batter which makes the cake tough, and frosting a warm cake which causes the buttercream to melt and crack.
Why does this Rainbow KitKat Cake recipe use melted dark chocolate in the batter instead of cocoa powder?
Melted dark chocolate adds a smooth, glossy texture and enhances the chocolate flavor, while also helping to bind the KitKat pieces into the batter for an even crumb.
Can I make Rainbow KitKat Cake ahead of time and how should I store it?
Yes. Bake and cool the layers, then wrap them individually and refrigerate. Assemble and decorate up to 24 hours before serving; keep the finished cake refrigerated and bring to room temperature before slicing.
What texture and appearance should I look for when making Rainbow KitKat Cake?
The cake layers should be light, airy, and spring back when pressed lightly. The KitKat base should be glossy and firm, and the final frosting should be smooth with vibrant, even swirls of rainbow buttercream.
What does the YouTube channel Unknown specialize in?
The YouTube channel Unknown focuses on fun, visually striking dessert tutorials that often incorporate popular snack foods like KitKat and Oreo into creative cake designs.
What is the cooking philosophy and style of the YouTube channel Unknown?
The channel emphasizes step‑by‑step guidance, bright presentation, and making elaborate-looking cakes accessible to home cooks using everyday ingredients and clear visual cues.
Last updated: September 6, 2026
