Adapted from Mary Berry’s Frosted Walnut Layer Cake.
225g/8oz soft margarine
225g/8oz caster sugar
225g/8oz self-raising flour
2 teaspoons baking powder
100g/4oz walnuts, finely chopped
For the frosting:
2 egg whites
350g/12oz caster sugar
4 tablespoons water
14 teaspoon cream of tartar
Pre-heat the oven to 160C/325F/Gas 3. Lightly grease and line the base of three 20cm/8in sandwich tins with greased greaseproof paper.
Measure all the ingredients for the cake into a large bowl and beat them together until they are thoroughly blended. Divide equally between the tins and level the surfaces. Bake in the pre-heated oven for about 25- 30 minutes, until the cakes are golden and springy to the touch. Turn out and leave to cool on a wire rack.
For the frosting: measure all the ingredients into a bowl over a pan of hot water and whisk, using an electric or rotary whisk, for 10-12 minutes, until thick. Sandwich the cake layers together with a little of the frosting, then use the remainder to cover the top and sides of the cake, swirling the icing to form soft peaks. Decorate with the walnut halves.