Description

This Chocolate Peanut Butter Cake is a rich, decadent dessert designed to serve a large crowd, combining a moist chocolate cake with fluffy peanut butter frosting. Topped with mini Reece’s Peanut Butter Cups and finished with a drizzle of melted chocolate and peanut butter, it’s an impressive treat perfect for parties or special occasions. The cake balances the deep chocolate flavor with a hint of saltiness in the frosting, making each bite irresistible.

Ingredients

Scale

Cake Ingredients

1 3/4 cups plain / all-purpose flour
3/4 cup unsweetened cocoa powder
1 1/2 tsp baking powder
1 1/2 tsp baking soda (bi-carb soda)
2 cups white sugar (or caster/superfine sugar)
1 tsp cooking/kosher salt
2 large eggs
1 cup milk (low or full fat)
1/2 cup vegetable oil (or plain flavoured oil like canola, grapeseed, rapeseed, sunflower)
2 tsp vanilla extract
2 tsp instant coffee powder (optional)
1 cup boiling water

Frosting Ingredients

250g / 2 sticks unsalted butter, softened
4 cups (500 g) soft icing sugar / powdered sugar, sifted
1/2 cup (120 g) smooth peanut butter (spread, not pure)
1/4 tsp cooking/kosher salt
1 tbsp milk

Topping Ingredients

1/2 cup chocolate chips or melts (semi-sweet chips)
2 tbsp cream (thickened/heavy or pure, not low fat)
3 tbsp peanut butter (warmed in microwave to make it runny)
120g / 4 oz mini Reece’s Peanut Butter Cups
10+ miniature Reece’s Peanut Butter Cups, halved
1/4 cup salted peanuts, finely chopped

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Instructions

Preheat and Prepare Pan: Preheat the oven to 180°C (350°F) or 160°C fan. Grease a 23 x 33 cm (9 x 13 inch) metal cake pan with butter, then line it with baking paper, leaving an overhang to easily lift the cake out after baking.
Mix Dry Ingredients: In a large bowl, sift together the flour, cocoa powder, baking powder, baking soda, sugar, and salt. Mix until combined thoroughly.
Combine Wet Ingredients: In a separate bowl, beat the eggs lightly. Add milk, vegetable oil, vanilla extract, and instant coffee powder (if using), mixing well.
Make Cake Batter: Gradually add the wet ingredients to the dry ingredients, stirring gently until just combined. Pour in the boiling water slowly, stirring to create a smooth, thin batter that blooms the cocoa flavor.
Bake the Cake: Pour the batter evenly into the prepared pan. Bake in the preheated oven for approximately 45 minutes or until a toothpick inserted into the center comes out clean.
Cool the Cake: Allow the cake to cool in the pan for about 15 minutes. Then use the paper overhang to lift the cake out and transfer it to a wire rack to cool completely before frosting.
Prepare the Frosting: Beat the softened unsalted butter until creamy. Gradually add sifted icing sugar, peanut butter, salt, and milk, beating until smooth and fluffy. Adjust consistency with milk if needed.
Frost the Cake: Spread the peanut butter frosting evenly over the cooled chocolate cake using a spatula or knife.
Make Chocolate Peanut Butter Drizzle: Gently melt chocolate chips with the cream in a heatproof bowl over simmering water or microwave in short bursts, stirring until smooth. Mix in warmed peanut butter until fully combined.
Decorate: Drizzle the melted chocolate-peanut butter mixture over the frosted cake. Scatter mini Reece’s Peanut Butter Cups and halved mini Reece’s cups on top, then sprinkle with finely chopped salted peanuts for texture and visual appeal.
Serve: Allow the drizzle to set slightly before slicing the cake into 20 to 25 small slices due to its richness. Serve and enjoy!

Notes

The included recipe video demonstrates the entire process and offers helpful tips for best results.
This cake is rich and decadent, so small slices are perfect for serving a large crowd of 20 to 25 people comfortably, with the potential to serve up to 30.
The touch of salt in the frosting enhances the sweetness and balances the flavors beautifully.
For round cake pans, see additional tips in the original recipe video or guide to adjust pan size and baking times.
Instant coffee powder is optional but helps intensify the chocolate flavor without making the cake taste like coffee.
Use smooth peanut butter spread, not pure peanut butter, for a creamier frosting texture.

Nutrition

Serving Size: 1 slice (approx. 1/25 of cake)
Calories: 395 kcal
Sugar: 41 g
Sodium: 258 mg
Fat: 21 g
Saturated Fat: 8 g
Unsaturated Fat: 11 g
Trans Fat: 0.3 g
Carbohydrates: 51 g
Fiber: 2 g
Protein: 5 g
Cholesterol: 38 mg