Preheat oven. Begin by preheating the oven to 180°C/160°C fan/350°F/Gas 4. Grease an 18cm square cake tin and line the base with baking parchment.

For the genoise sponge mixture. Melt the butter in a pan and set it aside to cool slightly. Whisk the eggs and sugar at full speed in a large bowl until the mixture becomes pale, mousse-like, and thick enough to leave a trail when the whisk is lifted. Sift the flour together into a bowl. Carefully fold half of the flour into the egg mixture, gently pour half of the cooled butter around the edge, and then fold in. Repeat with the remaining flour and butter. Pour the mixture into the prepared tin.

To bake the genoise sponge. Bake in the oven for 35–40 minutes or until the cake is well-risen and the top springs back when lightly pressed. Allow it to cool in the tin for a few minutes, then turn it out, peel off the parchment, and finish cooling on a wire rack.

To cut the Genoise sponge. Horizontally cut the cold cake in half and sandwich the slices with the coffee buttercream.

Assemble. Use any filling and topping you like or continue below with Mary Berry Mokatines recipe using the Genoise Sponge

For the mokatines

To create the coffee icing (Optional). Melt the butter in a small pan, remove from heat, and stir in the coffee powder until dissolved. Add the icing sugar and beat until smooth and glossy. Set aside to thicken.

For the crème au beurre moka (Optional). Heat sugar and water in a small heavy-based pan until the sugar dissolves. Bring to a boil and boil steadily for 2–3 minutes until the syrup is clear. Pour the syrup over whisked egg yolks, stirring until thick and cold. In another bowl, cream the butter until soft, gradually beat the egg yolk mixture, and stir in the coffee essence. Spoon into a piping bag with a No. 7 star nozzle.

For the fondant icing (Optional). Beat the fondant icing with a wooden spoon until smooth. Gradually add water and food colouring to make a coffee-coloured glaze. Carefully spoon the glaze into the centre of the tops of the cakes and leave to set.

Assemble the mokatines. Trim the edges and cut the cake into 9 equal squares. Heat apricot jam in a pan, then pass it through a sieve into a small bowl. Brush the sides of the cakes with apricot jam and press chopped, toasted nuts around the sides. Pipe tiny rosettes of crème au beurre moka around the top edges of the cakes, piping them closely together to prevent the fondant icing from running off. Pipe tiny rosettes around the bottom edges of the cakes.