Decadent Chocolate & Vanilla Layer Cake

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🍫🍰 Decadent Chocolate & Vanilla Layer Cake

A gorgeous two-flavor celebration cake with moist chocolate and vanilla sponges, layered with luscious frosting and perfect for birthdays, parties, or special occasions.

⭐ Ingredients

For the Vanilla Cake (Two 8-inch layers)

  • 2 ½ cups all-purpose flour
  • 2 ½ tsp baking powder
  • ½ tsp baking soda
  • ½ tsp salt
  • 1 cup unsalted butter, softened
  • 1 ½ cups granulated sugar
  • 4 large eggs, room temp
  • 1 tbsp vanilla extract
  • 1 cup buttermilk (or 1 cup milk + 1 tbsp vinegar)

For the Chocolate Cake (Two 8-inch layers)

  • 1 ¾ cups all-purpose flour
  • ¾ cup unsweetened cocoa powder
  • 2 cups granulated sugar
  • 2 tsp baking soda
  • 1 tsp baking powder
  • 1 tsp salt
  • 1 cup buttermilk
  • ½ cup vegetable oil
  • 2 eggs
  • 2 tsp vanilla extract
  • 1 cup hot coffee (or hot water)

For the Frosting (Chocolate-Vanilla Swiss Buttercream)

(This makes enough for filling + crumb coat + decorating)

  • 6 large egg whites
  • 1 ½ cups sugar
  • 2 cups unsalted butter, softened & cubed
  • 1 tbsp vanilla extract
  • Pinch of salt
  • ½ cup melted cooled dark chocolate (for the chocolate half)

👩‍🍳 Instructions

1. Make the Vanilla Cake

  1. Preheat oven to 350°F (175°C). Grease and line two 8-inch pans.
  2. In a bowl, whisk flour, baking powder, baking soda, and salt.
  3. In another bowl, cream butter + sugar for 3–4 minutes until fluffy.
  4. Add eggs one at a time, mixing well.
  5. Add vanilla.
  6. Alternate adding dry ingredients and buttermilk, starting and ending with dry.
  7. Divide batter between the two pans.
  8. Bake 22–27 minutes, or until a toothpick comes out clean.
  9. Cool completely.

2. Make the Chocolate Cake

  1. Keep oven at 350°F (175°C). Prepare two 8-inch pans.
  2. Whisk flour, cocoa, sugar, baking soda, baking powder, salt.
  3. Add buttermilk, oil, eggs, vanilla → whisk smooth.
  4. Slowly pour in hot coffee (batter will be thin—this is correct).
  5. Divide into pans.
  6. Bake 25–30 minutes.
  7. Cool completely.

3. Make the Frosting (Swiss Buttercream)

  1. Add egg whites + sugar to a heatproof bowl.
  2. Put bowl over simmering water (double boiler) and whisk until sugar is fully dissolved (140–160°F).
  3. Remove from heat; whip on high for 8–10 minutes until glossy and stiff.
  4. Add butter a little at a time until smooth.
  5. Add vanilla + salt.
  6. Divide frosting:
    • Half left vanilla
    • Half mixed with melted, cooled chocolate for chocolate frosting

4. Assemble the Cake

Layer Order (from bottom):

  1. Chocolate cake
  2. Vanilla frosting
  3. Vanilla cake
  4. Chocolate frosting
  5. Chocolate cake
  6. Vanilla frosting
  7. Vanilla cake
  8. Finish with chocolate OR vanilla frosting on outside (your choice)

Assembly Steps

  1. Trim domes for flat layers (optional).
  2. Spread a thin layer of frosting between each layer.
  3. Do a crumb coat around the entire cake; chill 20 minutes.
  4. Frost with final thick, smooth layer.
  5. Decorate with swirls, chocolate shavings, ganache drip, or sprinkles.

🍽️ Serving

  • Best served at room temperature for soft, creamy frosting
  • Slice with a hot knife for clean layers

🧊 Storage

  • Refrigerate up to 4–5 days (cover to prevent drying)
  • Freeze (individual slices or whole cake) up to 2 months

⭐ Variations

  • Marble the frosting on the outside for a two-tone swirl effect
  • Add chocolate ganache drip for dramatic effect
  • Fill with fresh berries or chocolate chips
  • Use cream cheese frosting instead of Swiss buttercream

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