Baking the pastry before adding the filling prevents the base becoming soggy during cooking.
Crush a sheet of greaseproof paper lightly into a ball. Open out the paper, then lay it inside the pastry shell.
Spread a layer of baking beans or rice over the paper, then press down gently so that the beans or rice and the paper rest firmly against the sides of the flan.
Bake according to the time specified in the recipe, or until firm. Remove the beans or rice and paper.
If indicated in the recipe, rebake until the pastry looks dry and is evenly coloured.