The edges of a pie crust are always at risk for overbrowning, especially when it comes to pies that are blind baked before the filling is added to them. The edges of a pie crust are often a bit closer to the heat source of the oven than other parts of the pie and they are not buffered by a filling or a pie plate, so even an underbaked pie can develop an over-browned edge. Fortunately, it is east to control the browning of that edge by using a pie shield.
A pie shield is a round disc – usually made of aluminum or silicone – that lightly sits over the rim of a pie and shields that edge from the heat oven the oven. It should be applied towards the end of baking, once the crust is browned, and should be left in place until you take the pie out of the oven. You can buy pie shields and it is nice to have them on hand if you find you need them a lot, however you can also make them.
To make one, simply wrap a ring of aluminum foil around the outside of your pie plate and fold about 1-inch over the edge of the crust, towards the center of the pie. The ring can be applied before you put the pie in the oven, but the foil should only be bent to cover the crust once the edge is browned. You can also cut the rim off of an aluminum pie plate (the disposable kind) and, after flattening it slightly, can set that over the edge of your crust.
I will follow all this up by saying that I don’t mind some extra browning on my pie crusts, even if I press the crust too thin and get a slightly burnt spot. While I do try to avoid burning my baked goods, I love a well-cooked, crispy pie crust. I mention this because pie crusts don’t brown as quickly as you might think and I’ve had a lot of underbaked pies. Be sure not to put your pie crust shield into action until the pie crust is as brown as you want it to be. The pie crust shield should prevent burning, but applying it too early could potentially lead to a pie crust that isn’t as browned as it should be.