Can Brie En Croute be made with pie crust?

I wouldnt....
Unless the dough is really thin, dont even bother.
The reason people use puff pastry is because its light, flaky, and thin, and will hardly interfere in the cooking process since its thiner.
Also it looks great once cooked.

A pie crust if not very flexible will bake and break. If too thick the dish may be lost. If too thin it wold hold up. The pie crust can burn or become hard after so much baking especially if its not thin.
Also pie crust is heavier.
Unless you have done this before i wouldnt risk is. I had a chef once make salmon en croute without puff pastry and it was horrible , the fish would get damaged , the crust would break , the crust was heavy , and the dough stook to the baking sheet.
Was not a pleasurable experience.

Did you get any of that first response. Read it twice and still didn't male much sense. Anyway i don't see why it wouldn't work with a nice flaky pie crust. Your just melting cheese not cooking a fish. I did get that part. And some of those Brie melter crocks don't recommend puff pastry because it sticks to the bottom of the lid. They use pie crust. Ends up looking like a pot pie. Even if it doesn't work the cheese will be melted goodness which is the whole point. The pastry just keeps the cheese from running everywhere and looks pretty.

Yes just roll it as thin as possible.

Most pie crusts are too heavy for the cheese and will not taste right. Also the pie crust bakes up harder than puff pastry and will ruin the flavors you are looking for. You can buy frozen puff pastry sheets at the market and they work out quite well.