Peanut butter chocolate cake

Preheat oven to 180° C. Grease a deep 20cm square cake pan, line base and sides with baking paper.

Stir cocoa and the water in a small heatproof jug until cocoa dissolves. Cool 10 mins.

Beat butter, sugar and extract in a small bowl with an electric mixer until pale and fluffy. Beat in eggs, one at a time, then cocoa mixture and peanut butter until combined (mixture may look curdled at this stage). Beat in sifted dry ingredients and buttermilk, in two batches, until smooth. Spread mixture into cake pan.

Bake cake 1¼ hours or until a skewer inserted into the centre comes out clean. Stand cake in pan 5 mins before turning, top-side up, onto a wire rack to cool completely.

PEANUT BUTTER GANACHE

Place chocolate and peanut butter in a medium heatproof bowl. Heat cream in a small saucepan until almost boiling, pour over chocolate mixture, whisking until smooth. Cover, refrigerate for 1 hour, stirring occasionally, until mixture is chilled and thickened.

Beat cold peanut butter ganache with an electric mixer until pale and fluffy. Spread ganache on top of cooled cake, top with peanut-butter-filled chocolate.