300g softened unsalted butter, plus extra for greasing 250g caster sugar 4 eggs 250g self-raising flour 2 tsp baking powder 2 tbsp double cream icing sugar, for dusting Preheat the oven to 180°C/gas mark 4, and grease and line a loose-bottom 20cm square cake tin. In a large mixing bowl, cream the caster sugar into the butter for 3-4 mins, until creamy and smooth. Beat in the eggs, one at a time, then sift in the flour and fold into the mixture. Add the baking powder and double cream, and stir. Transfer the mixture to the tin and level out to fit. Bake for 30-35 mins, until risen and golden and an inserted metal skewer comes out clean. Allow to cool in the tin, then place on a serving plate. Dust with icing sugar, using a sieve, before serving.