Preheat the oven to 175 degrees C. Mix 2 cups flour and icing sugar, add the butter and mix everything well. Put the dough in the baking dish, evenly spreading along the bottom of the form. Bake for 15 to 20 minutes or until golden brown.
Beat eggs, sugar, 4 tablespoons of flour, lemon juice and lemon zest. Pour the mixture onto the baked crust.
Bake for 20 minutes, then sprinkle with powdered sugar.