Sieve together the flour and baking powder. Tip the butter ... film and microwave on full power for four minutes (or until the sponge begins to shrink from the sides and is springy to the touch).

deep sponge tins, lightly greased and the bases lined with baking paper. Preheat the oven to 170C/325F/Gas 3. Take a very large mixing bowl, put the flour and baking powder in a sieve and sift it ...