There is nothing more disappointing to me than cutting into a beautiful pie, only to find a raw bottom crust. Bakers often forget that it takes time for heat to penetrate a pie, and that unlike a cake, a baked top does not necessarily mean a baked bottom. How do you assure your crust is baked on the bottom? Pre-baking is the key. This is known in the business as blind-baking.
Blind-baking allows you to pre-cook a pie shell, either fully or partially, so that once the filling goes in it is only necessary to bake the pie as long as the filling requires. In some cases, like cream pies, the filling isn’t baked at all, in which case blind-baking is essential.
To blind bake a pie shell, form the dough in the pan, decoratively flute the edges, and chill until firm. This chilling assures that the crimped edge will keep its shape in the hot oven. (If the dough is frozen the protein will solidify before the fat gets a chance to melt.)
Line the dough with foil, parchment paper or heavy-duty plastic wrap (it shrinks, but doesn’t melt), then fill it to the rim with dried beans or rice. The weight of this filling is important to keep the shell from melting, shrinking, and bubbling up. Strings of ceramic pie beads do not work, because they do not support the dough on the sides of the pan. Aluminum pie weights work if you use enough of them, but they are expensive, and I have seen stray weights crack a tooth. Beans and rice are easier, cheaper, and safer.
Bake at 350˚F until the edges are golden brown. At this point the shell is half cooked and can be used for several recipes in which the filling needs only to be cooked a short while. To cook it completely, carefully remove the weights and return to the oven until the bottom is browned.
Blind baking does not work for a double crust pie because the top crust must be pinched and crimped to the bottom crust, which can only be done if the dough is raw. So to help ensure the bottom of a double crust pie is cooked, you must be sure to bake it long enough. How long is that? It should be long enough to get the filling really bubbly, and to turn the top crust a deep, dark golden brown. When you think your pie is at that point, leave it in another 5 minutes. Then, if your oven allows it, move the pie off the rack and cook it 5 more minutes directly on the floor of the oven. This final direct burst of heat is my perfect crust insurance.