Soften and dice the unsalted butter which is being used for the sponge. Sift the plain flour. Also soften and dice the unsalted butter being used for the vanilla buttercream icing. Sift the icing sugar.
- 1 Heat the oven to 180°C/350°F/gas 4 (160°C for fan ovens). Line the base of one 20-22cm square cake tin per cake being made with baking paper and grease the sides with butter.
- 2 For the sponge, using a handheld electric beater cream the butter until soft, then beat in the sugar until pale.
- 3 Whisk in the eggs, one at a time, and fold in the remaining ingredients until combined and smooth.
- 4 Tip the mixture into the tin(s), smooth the top and bake for 40-50 minutes or until a skewer inserted into the centre of the cake comes out clean.
- 5 Allow the cake to stand for 10 minutes in the tin before transferring to a wire rack to cool completely.
- 6 To make the icing, put all the ingredients in a food processor and whizz until light and fluffy.
- 7 Place the cooled cake on a plate, spread the icing over the top, then cut into squares.
- Average per serving
- Calories 320.0kCal