Butter 1 side of a square of aluminum foil to fit inside the chilled tart and place it, buttered side down, on the pastry. Fill with beans or rice. Bake for 20 minutes. Slowly lift the edge of the foil, if it sticks it needs to dry out more. Put back in oven and check every 2 minutes until the foil lifts off cleanly. Remove the foil and beans. Prick the tart all over with the tines of a fork, and bake again for 20 to 25 minutes more, or until lightly browned. If the edge is browning too quickly, cover it with a ring of foil or pie shield. Allow to cool to room temperature.