Preheat the oven to 180C/350F/Gas 4.
To make the base, cream the butter and gradually add the caster sugar. Beat until pale, soft and light. Add the egg, a little at a time, beating well after each addition, before adding the vanilla extract.
Sift together the dry ingredients and stir gently into the creamed mixture.
Mix everything together lightly and add the milk to moisten. Spread the mixture into the prepared tin, smoothing it out to the edges. Spread the jam gently over the cake mixture and sprinkle with the raspberries. You may need to press them down gently into the cake mixture.
Make the topping. Cream the butter and sugar together as before until pale, soft and light. Add the beaten eggs gradually, beating well after each addition. Mix together the coconut and rice flour and fold into the mixture. Spread gently but evenly over the raspberries and bake in the oven for about 35-40 minutes or until a skewer comes out cleanly.
Leave to cool in the tin and cut into 24 biscuits.