1 tsp baking powder
225g/8oz caster sugar
100g/3½oz caster sugar
350g/12oz caster sugar
¼ tsp cream of tartar
250g/9oz icing sugar
225g/8oz self-raising flour, sifted
½ tsp vanilla extract
100g/3½oz walnuts, finely chopped
10 walnut halves
225g/8oz butter, softened, plus extra for greasing
125g/4½oz butter, softened
4 large free-range eggs, beaten
2 large egg whites
2 tbsp milk