Ingredients
180g/7oz plain white flour
90g/3½oz granulated sugar
7ml/1½ tsp baking powder
60g/2½oz unsaturated margarine
2 eggs, whites only
1 tsp vanilla essence
675g/1½lb blackcurrants, fresh or frozen (thawed)
For the topping:
2 tbsp plain, white flour
500g/18oz low-fat natural yoghurt or fromage frais
1 egg, lightly beaten
125g/5oz granulated sugar
2 tsp grated lemon or orange rind
1 tsp vanilla essence

Method
1. In food processor or mixing bowl, combine flour, sugar, baking powder, margarine, egg whites and vanilla essence, mix well.
2. Press into bottom of 25cm/10in square cake tin, or flan dish.
3. Sprinkle with blackcurrants.
4. For the topping: in a bowl, sprinkle flour over yoghurt or fromage frais. Add egg, sugar, rind and vanilla essence; mix until smooth. Pour over blackcurrants.
5. Bake in 180C/350F/Gas 4 oven for 60 to 70 minutes or until golden. Serve warm or cold.