When making custard pies you will need to par-bake your pie crust. Once you have lined your pie tin with your pie dough dock it lightly by poking lots of holes in the shell with a fork. Then place a coffee filter on top of the your pie dough. This will act as parchment paper. Place a pie tin of the same size on top of the of coffee filter lined pie dough. Fill the layered pie tin with something to weigh it down slightly such as an empty ramekin. If the weight is too light the pie shell may still puff up and if the weight is too heavy it may squish your pie shell. In a pinch, a sheet pan can work as a weight but sheet pans might be a little too heavy plus it’s difficult to check for doneness.
As a last resort if you do not having anything oven safe to weight down the layered pie tin, you can flip the entire package upside-down and bake it like that in the oven. Gravity will act as your weight. This is usually a good method for mini pie shells. Be sure to check your pie shell every once in a while throughout the baking process and press down on the entire package if you notice the pie shell starting to puff up.
Those methods do not work if you have a fluted edge. In that case, you will have to use a coffee filter that is as big as the entire pie shell and fill it with baking beans. These beans are usually called pie weights are available at most baking and pastry supply stores. As a last resort, you may be able to use dried beans (pinto beans work fine), peas, or rice but be aware that these items could get burned or may be unusable for other uses after baking. You need to fill the pie shell with baking beans all the way up to the edge – if you don’t the pie shell’s sides could slump during the baking process.
After your par-baked shell has completely cooled, you may want to brush white chocolate on the surface of your pie shell. The white chocolate acts as a barrier to moisture from the filling keeping your pie shell crisp for a longer period of time.