1. Line and grease the tin, pre-heat oven to 180 degrees
2. Rub the butter and flour together into crumbs, then add the egg to bind. Wrap in cling film and pop in the fridge.
3. Melt the sugar, lemon juice and zest in a pan on low heat. Mix the egg yolk to the cornflour mix and add to the pan, add the boiling water and stir at a simmer until thickened. Leave to cool
4. Mix the melted butter with eggs and sugar, add the coconut and baking powder.
5. Roll the pastry out thinly and put a layer in the bottom of your tin. No need to blind bake. Pour over the slightly cooled lemon filling and spread in an even layer. Then spread over the topping in a thin layer over the top.
6. Bake for 30 minutes until firm and golden. Turn out gently and cut into 16 squares whilst still warm.
Credit: BBC Good Food
For the Pastry:
75g plain flour
35g butter or margarine
For the Filling:
Zest and juice of 1 lemon
1 egg yolk
2 tsp cornflour, mixed with a little milk
90ml boiling water
For the Topping:
25g butter, melted
100g dessicated coconut
¼ tsp baking powder