Mocha Layer Cake with Chocolate-Rum Cream Filling

 

Mocha Layer Cake with Chocolate-Rum Cream Filling: A Masterpiece Recipe

There are desserts that satisfy, and then there are desserts that impress. A mocha layer cake with chocolate-rum cream filling is firmly in the latter camp—a show-stopping creation that’s rich, indulgent, and perfect for celebrations or when you want to wow a crowd. With its bold coffee flavor, dark chocolate complexity, and a hint of rum in the luscious cream filling, this cake is layered luxury.

In this comprehensive recipe, we’ll walk through each step, from baking the perfect mocha sponge to preparing a silky chocolate-rum cream filling, and finally assembling and decorating a dessert worthy of any special occasion. Even novice bakers can follow along and create something truly memorable.

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Table of Contents

1. Introduction

2. Ingredients

3. Equipment Needed

4. Baking the Mocha Cake Layers

5. Making the Chocolate-Rum Cream Filling

6. Preparing the Mocha Syrup (Optional but Recommended)

7. Making the Mocha Buttercream Frosting

8. Assembling the Cake

9. Decorating and Finishing Touches

10. Storage Tips

11. Variations

12. Troubleshooting & Expert Tips

13. Final Thoughts

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1. Introduction

Mocha and rum are a match made in dessert heaven. This cake celebrates that combination with soft, fluffy mocha sponge layers, filled with a rich, ganache-style cream spiked with dark rum, then wrapped in a luxurious mocha buttercream. Each bite is a play of textures and flavors—bittersweet, boozy, smooth, and satisfying.

Let’s get started!

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2. Ingredients

For the Mocha Cake (Makes 3 8-inch layers):

• 2 ½ cups (315g) all-purpose flour

• 1 tbsp baking powder

• ½ tsp baking soda

• ½ tsp salt

• ¾ cup (75g) unsweetened cocoa powder

• 1 tbsp instant espresso powder

• 1 cup (240ml) boiling water

• 1 cup (230g) unsalted butter, room temperature

• 2 cups (400g) granulated sugar

• 4 large eggs, room temperature

• 1 tbsp vanilla extract

• 1 cup (240ml) buttermilk, room temperature

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For the Chocolate-Rum Cream Filling:

• 10 oz (285g) semi-sweet or dark chocolate (60–70%), finely chopped

• 1 ¼ cups (300ml) heavy cream

• 2 tbsp unsalted butter

• 3 tbsp dark rum (or to taste)

• Pinch of salt

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For the Mocha Syrup (optional):

• ½ cup (120ml) strong brewed coffee or espresso

• ¼ cup (50g) sugar

• 1 tbsp dark rum

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For the Mocha Buttercream Frosting:

• 1 cup (230g) unsalted butter, room temperature

• 3 ½ cups (440g) powdered sugar, sifted

• 1 tbsp cocoa powder

• 1 tbsp instant espresso powder

• 2 tbsp heavy cream (or milk)

• 1 tsp vanilla extract

• Pinch of salt

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3. Equipment Needed

• 3 8-inch round cake pans

• Parchment paper

• Electric mixer (stand or hand-held)

• Offset spatula and bench scraper

• Fine-mesh sieve

• Serrated knife (for leveling)

• Cooling racks

• Mixing bowls

• Whisk

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4. Baking the Mocha Cake Layers

Step-by-Step Instructions:

1. Prep the pans:

   • Grease and line three 8-inch round pans with parchment.

   • Preheat oven to 350°F (175°C).

2. Make the mocha base:

   • In a small bowl, whisk cocoa powder and espresso powder with boiling water until smooth. Let cool slightly.

3. Sift dry ingredients:

   • In a medium bowl, sift together flour, baking powder, baking soda, and salt.

4. Cream butter and sugar:

   • In a large bowl, beat butter until creamy, about 2 minutes.

   • Gradually add sugar and beat until fluffy—3 to 4 minutes.

5. Add eggs and vanilla:

   • Beat in eggs one at a time, scraping down sides of the bowl.

   • Add vanilla and the cooled mocha mixture.

6. Alternate dry and wet:

   • Add flour mixture in 3 additions, alternating with buttermilk in 2 additions. Mix until just combined.

7. Divide and bake:

   • Divide batter evenly among the prepared pans.

   • Bake for 25–30 minutes, or until a toothpick comes out clean.

8. Cool:

   • Let cakes cool in pans 10 minutes, then transfer to racks.

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5. Making the Chocolate-Rum Cream Filling

This rich filling is similar to a ganache but slightly lighter and perfect between cake layers.

Instructions:

1. Heat cream:

   • In a saucepan, heat cream and butter just to a simmer.

2. Melt chocolate:

   • Place chopped chocolate in a heatproof bowl. Pour hot cream over and let sit 2 minutes. Stir until smooth.

3. Add rum:

   • Stir in dark rum and a pinch of salt. Let cool to room temperature, then refrigerate for 1–2 hours until thickened to a spreadable consistency.

Note: Don’t let it harden too much. If it firms up, let it sit at room temperature or gently rewarm over a water bath.

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6. Preparing the Mocha Syrup (Optional)

For extra moisture and coffee kick, brush each layer with mocha syrup.

How to Make:

1. In a small saucepan, combine brewed coffee and sugar. Heat until sugar dissolves.

2. Remove from heat and stir in rum.

3. Let cool completely.

Brush lightly on cake layers before assembly.

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7. Making the Mocha Buttercream Frosting

This is a classic American-style buttercream with espresso intensity and creamy depth.

Instructions:

1. Beat butter on medium-high speed until light and fluffy (about 3 minutes).

2. In a small bowl, dissolve espresso powder in 1 tbsp hot water. Add to butter along with vanilla.

3. Gradually add powdered sugar and cocoa powder.

4. Add cream to adjust consistency. Beat until smooth and fluffy.

5. Add a pinch of salt to balance sweetness.

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8. Assembling the Cake

Here comes the fun part—putting it all together.

Assembly Steps:

1. Level cakes (if necessary) with a serrated knife for even stacking.

2. Place the base layer on a cake board or stand. Brush with mocha syrup.

3. Spread the chocolate-rum filling evenly over the first layer (use about half). Leave a slight border to prevent overflow.

4. Repeat with second layer, syrup, and remaining filling.

5. Top with the third layer. Brush with syrup if desired.

6. Crumb coat the entire cake with a thin layer of mocha buttercream. Chill for 20–30 minutes.

7. Frost final layer of buttercream smoothly with an offset spatula. Use a bench scraper for a clean edge.

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9. Decorating and Finishing Touches

Ideas to Elevate Presentation:

• Pipe rosettes or swirls with leftover buttercream.

• Top with chocolate curls, shavings, or espresso beans.

• Dust with cocoa powder or edible gold.

• Drizzle with a ganache glaze (optional).

• Garnish with chocolate truffles or macarons for a dramatic finish.

Let your creativity run wild!

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10. Storage Tips

• Room temperature: Keep covered in a cake dome for up to 2 days.

• Refrigerator: Store in an airtight container up to 5 days. Bring to room temperature before serving.

• Freezing: Wrap individual slices in plastic and foil. Freeze for up to 2 months.

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11. Variations

• Booze-free: Omit rum in both filling and syrup. Add vanilla or almond extract instead.

• Flavored liqueur: Swap rum for Kahlúa, Frangelico, or Bailey’s for a twist.

• Different filling: Use mascarpone-espresso cream or whipped ganache.

• Sheet cake version: Bake in a 9x13" pan and layer horizontally.

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12. Troubleshooting & Expert Tips

Cake too dry?

• Don’t overbake. Use an oven thermometer for accuracy.

• Apply syrup for extra moisture.

Filling too soft?

• Chill longer or beat briefly to firm up.

Buttercream too sweet?

• Add a pinch of salt or a squeeze of lemon to cut sweetness.

Want a cleaner slice?

• Chill cake before slicing and use a hot knife.

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13. Final Thoughts

Baking a cake like this is more than just following a recipe—it’s a form of celebration. The mocha layer cake with chocolate-rum cream filling delivers depth of flavor, visual elegance, a