🍌🍫 Double Chocolate Banana Layer Cake

Ripe bananas add moisture and sweetness while cocoa and melted chocolate deliver serious chocolate depth. Two soft layers filled and frosted with a rich chocolate buttercream — perfect for birthdays, weekend baking, or whenever you need chocolate + banana comfort. 🎂✨

Ingredients

Dry & wet (cake)

• 3 ripe bananas, mashed (≈360 g peeled weight)
• 2 cups (250 g) all-purpose flour
• ¾ cup (75 g) unsweetened cocoa powder (prefer Dutch-processed for deeper flavor)
• 1 cup (240 ml) milk + 1 tsp lemon juice (let sit 5–10 min to make buttermilk)
• 2 large eggs (room temperature)
• 1 cup (200 g) granulated sugar
• ½ cup (110 g) packed brown sugar
• ½ cup (120 ml) vegetable oil (or neutral oil)
• 1 tsp vanilla extract
• 2 tsp baking powder
• 1 tsp baking soda
• Pinch of salt (about ¼ tsp)

Chocolate Buttercream (filling & frosting)

• 1 stick (113 g) unsalted butter, room temperature
• 3 cups (360 g) powdered (icing) sugar, sifted
• ½ cup (50–60 g) unsweetened cocoa powder, sifted
• ½ cup (90 g) melted dark chocolate (cooled slightly)
• 4–5 tbsp heavy cream (or milk), as needed for consistency
• Pinch of salt and 1 tsp vanilla extract

Equipment

• Two 8–9″ round cake pans (or one 9″ pan and slice horizontally)
• Parchment rounds, mixing bowls, whisk, spatula, electric mixer (hand or stand)
• Cooling rack, offset spatula or bench scraper for frosting

Step-by-step Instructions

1) Prep

1. Preheat oven to 175°C / 350°F. Grease and line two 8–9″ pans with parchment; lightly flour the sides (or spray with baking spray).
2. Make the milk + lemon juice mixture (buttermilk). Mash bananas until mostly smooth with a few small lumps for texture.

2) Mix dry ingredients

1. Whisk together flour, cocoa powder, baking powder, baking soda, and salt in a bowl. Sift if your cocoa is lumpy.

3) Combine wet ingredients

1. In a large bowl, whisk eggs with granulated sugar and brown sugar until combined (1–2 minutes). Add oil, vanilla, mashed bananas, and the buttermilk — mix until smooth.

4) Combine wet + dry

1. Fold the dry mixture into the wet mixture in two additions, mixing gently until just combined. Avoid overmixing — stop when there are no dry streaks. Batter will be thick and chocolatey.

5) Bake

1. Divide batter evenly between prepared pans. Bake at 175°C / 350°F for 30–35 minutes (start checking at 28 minutes). A toothpick inserted should come out with a few moist crumbs, not wet batter.
2. Cool in pans 10 minutes, then invert onto a rack to cool completely before frosting.

6) Make the chocolate buttercream

1. Beat room-temperature butter until pale and fluffy (2–3 minutes).
2. Sift in powdered sugar and cocoa powder, then beat on low to combine (to avoid a cocoa cloud). Add melted chocolate, vanilla, and salt. Add cream 1 tbsp at a time until you reach a spreadable, pipeable consistency. Beat 1–2 minutes on medium for a light, silky finish.

7) Assemble the cake

1. If layers are domed, level them with a serrated knife. Place first layer on your cake board/plate and spread a generous layer of buttercream (about 1/3 of total) — you can keep a thinner layer in the center to let banana moisture show through.
2. Repeat with the second layer. Crumb-coat the cake with a thin coat of buttercream and chill 15–30 minutes to set.
3. Finish frosting with remaining buttercream, smooth sides and top, or pipe decorative swirls. Optionally garnish with banana slices (lightly brushed with lemon to avoid browning), chocolate shavings, or chopped toasted walnuts.
4. Chill briefly to set the frosting before slicing (about 20–60 minutes). Serve at cool-room temperature for best texture.

Baker’s Notes & Variations

• Extra banana flavor: Fold ¼ cup finely mashed banana into the frosting (reduce cream slightly) for a banana-forward profile.
• Three layers: Divide batter into three 7–8″ pans or bake in one pan and slice horizontally for three layers; baking time will vary.
• Chocolate chips: Fold ¾ cup mini chocolate chips into the batter for pockets of melty chocolate.
• Nutty crunch: Add ½ cup toasted chopped walnuts between layers or sprinkled on top.
• Gluten-free: Use a cup-for-cup gluten-free flour blend; add 1/4 tsp xanthan gum if your blend lacks it.
• Lower sugar: Reduce granulated sugar by 10–15% if bananas are very ripe and sweet — texture may change slightly.

Health & Safety

• Use pasteurized eggs if serving to pregnant or immunocompromised guests, or ensure proper baking temperatures.
• Store frosted cake refrigerated if your kitchen is warm (but bring to cool-room temperature before serving for best flavor).
• Allergens: contains wheat, dairy, eggs; include nut warnings if using walnuts.

Nutrition & Ingredient Benefits (approx.)

Estimates per slice (12 slices) — approximate values and will vary by exact brands and portion sizes.

Storage, Make-ahead & Freezing

• Make-ahead: Bake layers up to 2 days ahead, wrap tightly, and refrigerate. Make buttercream and keep covered in the fridge; rewhip briefly before using.
• Refrigerate: Store assembled cake in the fridge up to 3–4 days. Bring to cool-room temperature (~30–60 min) before serving for best flavor.
• Freeze: Unfrosted layers freeze best — wrap in plastic and foil up to 2 months. Thaw overnight in the fridge then bring to room temp before frosting.

10 FAQs

1. Can I use overripe bananas? Yes — very ripe bananas are ideal for sweetness and moisture. If they’re super runny, drain a bit of excess liquid or reduce buttermilk slightly.
2. Why add lemon to milk? The lemon acid curdles the milk slightly to make a quick buttermilk — this tenderizes the crumb and aids rise.
3. Can I substitute butter for oil? Yes — replace half the oil with melted butter for flavor. Fully replacing oil with butter may yield a slightly denser crumb.
4. My cake is dense — why? Overmixing after adding flour or too little leavening can cause density. Measure ingredients by weight for best results.
5. How to prevent banana slices from browning on top? Brush with a little lemon juice (diluted) right before decorating.
6. Can I make this dairy-free? Use dairy-free butter and dairy-free chocolate; choose non-dairy milk and reduce powdered sugar liquid slightly.
7. Why is my frosting grainy? Powdered sugar clumps cause graininess — always sift powdered sugar and cocoa before beating.
8. How to get very dark chocolate flavor? Use high-quality dark cocoa for the batter and a higher-percentage dark chocolate in the melted chocolate (60–70%).
9. Can I pipe decorations? Yes — chill your buttercream slightly to firm up, then use a star or round tip for piping rosettes or borders.
10. What’s the best way to slice clean pieces? Chill the frosted cake 20–30 minutes, use a long serrated knife warmed under hot water and wiped dry between cuts.

Final thoughts

This Double Chocolate Banana Layer Cake balances moist banana-sweetness with deep chocolate richness. It’s forgiving, adaptable, and perfect for chocoholics who love fruit-forward undertones. Bake, frost, decorate, and enjoy — and don’t forget a good cup of coffee alongside! ☕️🍰

Want a printable recipe card, scaled versions (8, 12, or 24 servings), or a lighter whipped-cream filling instead of buttercream? Reply and I’ll create it for you. 🍌🍫

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