Preheat the oven to Gas Mark 4, 180°C, fan 170°C and butter two 20cm (8in) sandwich tins.
In a large mixing bowl, cream the butter and sugars together until smooth and fluffy. Add the eggs and sieve in the flour, bicarbonate of soda and baking powder. Mix well until all the flour is incorporated.
Add the peanut butter, 50g (2oz) of the chopped hazelnuts and beat well. Divide the mixture between the prepare sandwich tins and bake for 20-30 minutes in the preheated oven, until risen and golden.
When cooked, allow to cool in the tins on a wire rack.
Meanwhile, melt the chocolate either in a bowl set over hot water or in the microwave. In a medium bowl, whisk the double cream until thickened, then stir in the chocolate and the hazelnut spread.
Once the cakes have cooled, remove from the tins, then spread a layer of the cream on one cake and sandwich the other on top. Spread the remaining cream over the top and decorate with the remaining hazelnuts.
If you’re a coffee lover, you can make this into a mocha hazelnut cake by adding a couple of spoonfuls of strong black coffee to the cake mixture or the chocolate/hazelnut mixture – or both!
Inspired by Hannah Mack.