Mocha Hazelnut Layer Cake with Cocoa Buttercream
A sophisticated two-layer sponge cake that combines the warmth of roasted hazelnuts with subtle coffee notes, crowned with a silky cocoa and hazelnut buttercream. What sets this version apart is the toasted hazelnuts folded directly into the batter, delivering nutty texture throughout rather than just as garnish. The coffee is understated—just enough to deepen the chocolate notes without overpowering. Light, airy sponges built on proper creaming technique contrast beautifully against rich frosting. This cake suits afternoon tea, celebration desserts, or anyone craving coffee-and-chocolate comfort with grown-up sophistication. The roasting step is crucial: it transforms raw hazelnuts into deeply flavored, aromatic elements that define the cake's character. Serve at room temperature for best flavor and texture.
Ingredients
- 14 tbsp unsalted butter, plus extra for greasing
- 4 oz whole blanched hazelnuts, plus extra to decorate(optional)
- 1 cup golden superfine sugar
- 3 large eggs
- 1 ¾ cups self-rising flourplain flour + baking powder200g flour + 2 tsp baking powder
adjust volume slightly
- 1 tsp baking powder
- 1 tbsp espresso, cold made-up or Camp coffeestrong instant coffee1 tbsp powder dissolved in 1 tbsp hot watercaffeine
cooling step required
- 7 tbsp unsalted butter
- 1 cup powdered sugar
- 1 tsp cocoa powder
Instructions
- 1
Grease two round cake tins and line with baking paper. Preheat oven to 350°F/fan 325°F/gas 4.
- 2
Spread hazelnuts on a baking tray in a single layer and roast until toasted. Cool, then finely chop or pulse in a food processor and set aside.
- 3
Beat butter and superfine sugar with an electric whisk until light and fluffy.
- 4
Add eggs one at a time, beating well after each addition.
- 5
Sift flour and baking powder together, then fold gently into the mixture with a metal spoon until just combined.
- 6
Fold in the espresso and half the chopped nuts.
- 7
Divide between the prepared tins, level the surfaces, and bake until firm and risen.
- 8
Cool in the tins on a wire rack for 20 minutes, then turn out onto the rack to cool completely.
- 9
Beat butter and powdered sugar until pale and fluffy.
- 10
Sift in cocoa powder and fold through along with the remaining chopped nuts.
- 11
Place one cooled sponge upside-down on a serving plate. Spread half the buttercream over it.
- 12
Top with the second sponge and spread remaining buttercream on top.
- 13
Decorate with whole hazelnuts and chocolate shavings if desired.
Tips
Toast hazelnuts until their skins crack slightly and aroma peaks, roughly 15-20 minutes. Don't skip this—raw hazelnuts taste flat and bitter. Cool completely before chopping to prevent oil from being released.
Fold dry ingredients and coffee gently with a metal spoon, not a whisk. Overmixing develops gluten and deflates air bubbles built during creaming, resulting in dense, dry cake instead of light sponge.
Ensure sponges are completely cold before frosting. Warm cake melts buttercream, making it slide off. Use an offset spatula or palette knife for smooth, professional coverage.
Good to Know
Wrap cooled cake tightly in cling film or foil. Store at room temperature for up to 2 days, or refrigerate for up to 4 days. Buttercream-frosted cakes develop best flavor when brought to room temperature before serving.
Bake sponges up to 1 day ahead, wrap unfrosted, and store at room temperature. Make buttercream up to 24 hours ahead, refrigerate, and bring to spreadable consistency before assembly.
Serve at room temperature on a cake stand or plate. Pairs beautifully with strong black coffee, espresso, or hot chocolate. Slice with a warm, damp knife for clean cuts.
Common Mistakes
Don't rush the creaming stage—insufficient beating leaves cake dense rather than light and fluffy.
Don't mix the dry ingredients in vigorously—fold gently to preserve air and keep the sponge tender.
Don't assemble the cake while sponges are warm—buttercream will separate and slide off.
Substitutions
cooling step required
adjust volume slightly
FAQ
Can I make this cake ahead and freeze it?
Yes. Freeze unfrosted sponges wrapped tightly in cling film for up to 2 months. Thaw at room temperature before frosting. Frosted cake can be frozen for up to 1 month, though buttercream texture may change slightly upon thawing.
What if I don't have Camp coffee?
Dissolve 1 tablespoon instant espresso or strong instant coffee in 1 tablespoon hot water and let cool completely before folding in. Alternatively, use 1 tablespoon cooled freshly brewed strong black coffee.
Can I use oil instead of butter in the cake batter?
Not recommended. Butter is creamed for aeration and structure; oil won't incorporate air and will produce a denser cake. Butter is essential to this method. Use for buttercream substitution only.