Today is not for the faint of heart… Sure, this cake is not the healthiest option, but it is a sweet treat, not an everyday meal component. Make it. Eat it. Enjoy it. Share it.

Chocolate and Peanut Butter — a combination after my own heart. If you are craving an extra-rich chocolate cake with a thick peanut butter frosting and bites of crunchy salted peanuts, this cake is for you. This is one of the moistest cakes I have ever made. Every bite is sheer perfection.

This moist chocolate sponge with fluffy peanut-flavoured buttercream is inspired by Nigella Lawson's book Cook, Eat, Repeat, and it is a truly decadent celebration bake. If you have a free-standing food mixer and a food processor, this cake will be a doddle to make — though you can also make it by hand if you fancy a workout!

Do I Need Any Special Ingredients?

No, you don’t need fancy ingredients, but use the best quality you can afford for the ultimate flavour.

🔗 For help with conversions, see my Kitchen Conversions Guide.

Butter, salted: softened to room temperature for an ultra-moist crumb and fluffy frosting. Unsalted works too — just add a pinch more salt.

Soft light brown sugar: adds moisture and a slight toffee note to the sponge.

Golden caster sugar (superfine sugar): for sweetness and a fine, even crumb.

Cocoa powder (unsweetened cocoa powder): sift for a lump-free, intensely chocolatey batter.

Self-raising flour: gives lift without extra leavening faff.

Eggs: large, at room temperature so the batter emulsifies smoothly.

Vanilla paste/extract: rounds off both sponge and frosting.

Dark chocolate chips (semi-sweet): folded through for melty pockets.

Crunchy peanut butter: fabulous for texture; smooth works if you prefer a silkier finish.

Marshmallow fluff: the secret to a whipped, mousse-like peanut butter frosting.

Sea salt flakes (kosher salt): tiny pinch to sharpen flavours.

Salted peanuts (roasted peanuts): crushed for a savoury-sweet crunch on top.

Tips for the Best Cake

Use high-quality dark chocolate and cocoa powder for a deep, rich flavour.

Spread the batter evenly between tins to ensure uniform baking.

Allow cakes to cool completely before frosting to prevent melting.

Do not overbake — test with a skewer 5 minutes before the recommended time.

Room temperature butter is key for smooth, fluffy frosting.

Trim the tops of the cakes with a serrated knife for a level finish.

Chill the assembled cake for 30 minutes before slicing for clean edges.

Storage & Make-Ahead

Best enjoyed within a couple of days — it disappears quickly!

Store in the fridge if not serving immediately; bring to room temperature before serving.

Prepare frosting up to 1 day ahead and whisk briefly before using.

Freeze cakes (individually wrapped) for up to 5 months; defrost fully before assembling.

Chocolate Peanut Butter Cake

Prep: 30 mins | Cook: 18 mins | Servings: 16 slices

A rich, fudgy chocolate sponge layered with light, airy peanut butter frosting and finished with a crunch of salted peanuts.

Ingredients

• Chocolate Sponge: 200g salted butter, 250ml hot water, 50g cocoa powder, 100g soft light brown sugar, 125g golden caster sugar, 1 tsp vanilla paste, 2 large eggs, 225g self-raising flour, 100g dark chocolate chips
• Peanut Butter Frosting: 300g icing sugar, 150g soft unsalted butter, 200g crunchy peanut butter, 100g marshmallow fluff, 2 tsp vanilla extract, pinch sea salt, crushed salted peanuts for topping

Instructions

1. Preheat oven to 180°C (fan 160°C / gas 4). Butter two 20cm sandwich tins and line with baking parchment.
2. Melt the butter gently and mix with hot water.
3. Combine dry ingredients in a bowl or processor. Gradually add butter-water mixture, then eggs and vanilla. Mix until smooth, and fold in chocolate chips.
4. Divide batter between tins and bake 16–18 minutes (check with skewer).
5. Cool cakes completely in tins before frosting.
6. For frosting: Beat butter, peanut butter, and marshmallow fluff until smooth. Add vanilla and salt, then gradually beat in icing sugar until fluffy.
7. Assemble: Place one cake layer on a plate, spread a third of the frosting. Top with the second layer, repeat. Frost sides, smooth top, and decorate with crushed peanuts if desired.

🌟 Variations

Nut swap: Try almond or cashew butter instead of peanut butter.

Chocolate twist: Add white chocolate chips or drizzle melted chocolate over frosting.

Mini cupcakes: Divide batter into a muffin tin; bake 12–14 minutes.

Vegan: Use vegan butter, flax eggs (1 tbsp flaxseed + 3 tbsp water per egg), and dairy-free marshmallow fluff.

💡 Handy Hints / FAQs

Can I freeze this cake?

Yes — bake layers, wrap individually, and freeze for up to 3 months. Defrost completely before frosting.

Can I make the frosting ahead?

Absolutely — store in fridge up to 1 day and whisk briefly before using.

Can I use smooth peanut butter?

Yes, though crunchy adds texture and crunch.

Do I need special tins?

No, standard 20cm sandwich tins work perfectly; just line them well.

How to get really fluffy frosting?

Use room temperature butter and beat for 3–5 minutes until light and airy.

Would I Bake This Again?

Absolutely! Next time, I might add chopped Reese’s peanut butter cups between layers. What would you add?

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