Preheat the oven to 180ºC/ Fan 160ºC/ Gas 4. Add the softened butter and sugar to the bowl of a food mixer and beat until creamy, for about 10 minutes. Trickle in the egg a little at a time, beating it in as you go (you can also shake in a little flour also to prevent any curdling).
Fold in the remaining flour and add a little milk to loosen the mixture. Divide the mixture between the three tins and spread it out so level. Put in the oven and bake for 20-25 minutes, or until the sponge springs back when touched and a skewer comes out clean when poked into the middle. When ready, remove from oven and leave for 10 minutess then loosen around the edges with a knife and release from the tins. Sit them on a wire rack and leave to cool completely.
Transfer the sponges to a board and stamp out twenty rounds using the cutter (a metal one is easiest). To assemble, top ten of the rounds with the sliced strawberries (reserve some for topping,) add a dollop of cream then top with another sponge. Dust with sieved icing sugar and top with the remaining strawberries.