Heat the oven to 180C/fan 160C/gas 4. Beat the butter and sugar together until fluffy, beat in the eggs followed by the flour and baking powder. Add enough milk to the mixture so that it falls off a spoon easily then divide the mixture between 2 lined, 20cm sandwich tins. Bake for 35-40 minutes or until a skewer comes out cleanly. Cool on a wire rack.
Meanwhile, to make the filling, put the caster sugar in a pan with 6 tbsp water, heat gently until all the sugar has dissolved then simmer for a minute. Add half the strawberries and boil for a couple of minutes until you have a jammy consistency. Cool.
To fill the cakes, make a neat layer using the remaining strawberry halves on one cake, spoon the strawberry jam over and then spoon on a layer of cream. put the second cake on top and dust with icing sugar.