Chocolate chip traybake recipe
 Mary Berry's traybake is such an easy cake to make, and very quick to mix using the all-in-one method. It makes lots of portions so if you are cooking for a bake sale or party this is the one for you! For this recipe you will need a 23x30cm/9x12in traybake tin. 4 tbsp cocoa powder, sifted4 tbsp boiling water 4 large free-range eggs 225g/8oz baking spread, straight from the fridge, plus extra for greasing225g/8oz caster sugar225g/8oz self-raising flour 1 tsp baking powder 100g/3½oz dark chocolate chips 4 tbsp cocoa powder, sifted 4 tbsp boiling water 4 large free-range eggs 225g/8oz baking spread, straight from the fridge, plus extra for greasing 225g/8oz caster sugar 225g/8oz self-raising flour 1 tsp baking powder 100g/3½oz dark chocolate chips 250g/9oz full-fat mascarpone3 tbsp icing sugar, sifted 1 tsp vanilla extractcocoa powder, for dusting 250g/9oz full-fat mascarpone 3 tbsp icing sugar, sifted 1 tsp vanilla extract cocoa powder, for dusting Method Preheat the oven to 180C/160C Fan/Gas 4. Grease and line a 23x30cm/9x12in traybake tin with baking paper. For the sponge, measure the cocoa powder and boiling water into a large bowl and mix until smooth. Add all the remaining sponge ingredients, except the chocolate chips. Using an electric hand whisk, mix until light and fluffy. Stir in the chocolate chips. Spoon the sponge mixture into the prepared tin and level the surface. Bake in the middle of the oven for about 35 minutes, or until the cake is coming away from the sides of the tin and is springy to the touch in the middle. Leave to cool in the tin on a wire rack. To make the icing, mix the mascarpone, icing sugar and vanilla extract together in a bowl. Spread over the surface of the cold cake and dust with cocoa powder to finish. Slice into about 16 pieces – squares or fingers – to serve. Preheat the oven to 180C/160C Fan/Gas 4. Grease and line a 23x30cm/9x12in traybake tin with baking paper. Preheat the oven to 180C/160C Fan/Gas 4. Grease and line a 23x30cm/9x12in traybake tin with baking paper. For the sponge, measure the cocoa powder and boiling water into a large bowl and mix until smooth. For the sponge, measure the cocoa powder and boiling water into a large bowl and mix until smooth. Add all the remaining sponge ingredients, except the chocolate chips. Using an electric hand whisk, mix until light and fluffy. Stir in the chocolate chips. Add all the remaining sponge ingredients, except the chocolate chips. Using an electric hand whisk, mix until light and fluffy. Stir in the chocolate chips. Spoon the sponge mixture into the prepared tin and level the surface. Bake in the middle of the oven for about 35 minutes, or until the cake is coming away from the sides of the tin and is springy to the touch in the middle. Leave to cool in the tin on a wire rack. Spoon the sponge mixture into the prepared tin and level the surface. Bake in the middle of the oven for about 35 minutes, or until the cake is coming away from the sides of the tin and is springy to the touch in the middle. Leave to cool in the tin on a wire rack. To make the icing, mix the mascarpone, icing sugar and vanilla extract together in a bowl. Spread over the surface of the cold cake and dust with cocoa powder to finish. Slice into about 16 pieces – squares or fingers – to serve. To make the icing, mix the mascarpone, icing sugar and vanilla extract together in a bowl. Spread over the surface of the cold cake and dust with cocoa powder to finish. Slice into about 16 pieces – squares or fingers – to serve. Recipe tips Whisk the sponge for no more than 4 minutes as over-mixing can produce a dense cake. The un-iced cake freezes well. Wrap in a double layer of cling film and keep for up to 3 months.