The way we avoid soggy bottom involves two stages. Whether or not you are using a shop-bought shortcrust pastry, the secret to the crispy tart case is to line the tart tin with the pastry, prick the base with a form and place it in the freezer for 20 minutes to firm up. This stage avoids the pastry shrinking too much too quickly in the oven and also lets you blind bake without using baking beans. After freezing, we blind bake the pastry case for 20 minutes before adding the filling. EXTRA TIP: If you don't want to freeze the pastry, there's another way to ensure a crispy base. Once you lined your tart tin with the pastry and pricked the base with a fork, brush the bottom with lightly whisked egg white. Then leave the egg white to dry out. This will create a barrier between the filling and the pastry, ensuring that the filling doesn't seep into the base. Using this method, I would encourage you to use baking beans for blind baking, as the sides will not be cold enough and may collapse inwards.