When you put the effort into making a homemade pie crust for a Caramel Banana Cream Pie or other recipe that calls for a prebaked crust, it can be very disappointing if the crust that you worked so hard to make shrinks and gives your pie a less-than-perfect presentation. There are two ways that pie crusts can shrink and a couple of things that you can do to prevent it.
Pie crusts can shrink away from the bottom of a pie plate when you’re pre-baking the shell if you don’t put pie weights inside of the crust. Pie weights can be anything from a set of ceramic balls designed to be pie weights to a big batch of dried beans that are poured into a parchment-lined pie crust; pie weights are anything that will hold the pie crust down while it “sets” in the oven (more on How to Use Pie Weights). This typically happens with pastry crusts and you don’t need to use pie weights for graham cracker or crumb crusts.
Pie crusts can also shrink away from the sides of a pie plate, giving a crust a very uneven appearance and creating openings for filling to sneak into and make the crust soggy. This shrinkage can’t be solved with pie weights because it is primarily the result of not resting the pie dough enough. Just like when you are baking bread, gluten develops when you work with pie dough. Rolling out the dough and working with it to fit into your pie plate tightens up the gluten, and if you bake it straight away, that tightness will result in the crust shrinking and becoming tougher during baking. To prevent this type of shrinkage, rest the pie dough for about 5 minutes after you roll it out onto your work surface and before you press it into your pie plate. Once it is in the pie plate, put it back in the fridge (or leave it on the counter if your kitchen is very cool) to rest for about 15 minutes before baking. This resting gives the gluten time to relax and will help keep your crust from shrinking during baking.