Mocha Layer Cake with Chocolate-Rum Cream Filling

This elegant, grown-up cake pairs rich coffee-flavored layers with a luscious chocolate-rum cream filling and a smooth mocha frosting.

Ingredients

For the Mocha Cake Layers:

• 2 cups all-purpose flour
• 2 cups granulated sugar
• ¾ cup unsweetened cocoa powder (Dutch-process preferred)
• 2 tsp baking soda
• 1 tsp baking powder
• 1 tsp salt
• 2 large eggs, room temperature
• 1 cup buttermilk, room temperature
• 1 cup strong brewed coffee, cooled (or 1 tbsp instant espresso dissolved in 1 cup hot water)
• ½ cup vegetable oil
• 2 tsp vanilla extract

For the Chocolate-Rum Cream Filling:

• 1½ cups heavy whipping cream, chilled
• 8 oz semisweet chocolate, finely chopped
• 2 tbsp dark rum (or 2 tsp rum extract + 1 tbsp water for non-alcoholic)
• 1 tbsp granulated sugar
• Pinch of salt

For the Mocha Buttercream Frosting:

• 1½ cups (3 sticks) unsalted butter, softened
• 4–5 cups powdered sugar
• ½ cup unsweetened cocoa powder
• 3 tbsp strong brewed coffee, cooled
• 1 tbsp instant espresso powder dissolved in 1 tbsp hot water
• 2 tsp vanilla extract
• 3–4 tbsp heavy cream or milk
• Pinch of salt

For Decoration (Optional):

• Chocolate shavings or curls
• Cocoa powder for dusting
• Whole coffee beans

Instructions

Make the Cake Layers:

1. Preheat oven to 350°F. Grease and line three 8-inch round cake pans with parchment paper.
2. In a large bowl, sift together flour, sugar, cocoa powder, baking soda, baking powder, and salt.
3. In a separate bowl, whisk eggs, buttermilk, coffee, oil, and vanilla until smooth.
4. Gradually add wet ingredients to dry ingredients, mixing until just combined (batter will be thin).
5. Divide batter evenly among prepared pans. Bake 25–30 minutes, until a toothpick comes out clean.
6. Cool in pans 10 minutes, then turn out onto wire racks to cool completely.

Make the Chocolate-Rum Cream Filling:

1. Heat ½ cup of the heavy cream in a small saucepan until steaming (do not boil).
2. Place chopped chocolate in a heatproof bowl. Pour hot cream over chocolate and let sit 1 minute, then stir until smooth.
3. Stir in rum (or rum extract mixture) and salt. Let cool to room temperature.
4. In a chilled bowl, whip remaining 1 cup heavy cream with 1 tbsp sugar until soft peaks form.
5. Gently fold the whipped cream into the cooled chocolate mixture until uniform. Refrigerate 30 minutes to set slightly.

Make the Mocha Buttercream:

1. Beat softened butter on medium-high speed until creamy (about 2 minutes).
2. Sift together powdered sugar and cocoa powder. Gradually add to butter, mixing on low until combined.
3. Add cooled coffee, espresso mixture, vanilla, and salt. Mix until smooth.
4. Add heavy cream 1 tbsp at a time until frosting reaches spreadable consistency.
5. Increase speed to high and beat 1–2 minutes until light and fluffy.

Assemble the Cake:

1. Place one cake layer on a serving plate. Spread half the chocolate-rum cream filling evenly over the top.
2. Add second cake layer and spread with remaining filling.
3. Top with third cake layer. Apply a thin crumb coat of mocha buttercream over entire cake. Chill 20 minutes.
4. Frost cake with remaining buttercream. Use a spatula or bench scraper for smooth sides.
5. If desired, garnish with chocolate shavings, a dusting of cocoa, or whole coffee beans.