Our favorite way to have it in my home is with crisp flaky pie dough, made with butter, but baked separately, and served on the plate under the filling. You can make the pot pie covers a little bigger than the size of the casserole that you will serve them in, and bake them on a sheet pan till done. Then, you can slip them on top when you show the dish. The top will stay crisp and never get soggy this way. My pie crust for pot pie has extra butter in it, so that if I decide to put the crust on the pie and bake it in the oven, it will resist getting soggy.
Steam vents cut in the top also help.
This gives the gravy a little extra room to rise before it boils over. What you need to do is roll out the pie dough a little bigger than the casserole used, fold it in half and punch out a half circle the size of a quarter, for your steam vent, at the center of the fold. This allows you to position it precisely to fit. Then unfold the dough to cover the casserole, and fold under the excess dough, and pinch it to the rim. Use the remaining egg wash to brush on the piecrust before baking.