Grease the sides and base of a 15cm/6” square baking tin.  Set the oven to 180C/350F/gas mark 4.

Peel, quarter and core the apple.  Grate on the coarse blade of a grater and put into a small saucepan.  Add the sultanas or raisins and 1 tablespoon of the brown sugar.  Stir over a medium heat for about 5 minutes until the apple is cooked.  Set aside.

Melt the margarine in another pan.  Stir in the remaining sugar, oats and flour.

Spread half the oat mixture over the base of the tin pressing it down with the back of a spoon.  Spread the apple mixture on top. Now spoon over the remaining oat mixture gently spreading and pressing down evenly.

Bake for about 30 minutes until golden brown and firm on top.  Leave to cool a little before turning out and cutting into slices.