"Just wanted to second the parbaking recommendation. I've only made pot pie twice, but I basically treated the dough like a quiche dough and weighted it down with foil and beans for 20-25 minutes, then filled, topped and finished it. The only downside was that it was more challenging to get the top layer of dough to merge with the sides without breaking up or deforming the fluted edge."
I got a pretty decent result with a pre-baked oil crust filled with the good stuff, with a *biscuit* topping. Two kinds of crust, plus the leftovers from a roasted chicken earlier in the week, plus potatoes, mushrooms, and carrots cut up and oil-roasted for the purpose, plus medium-weight white sauce, plus a few (well, enough) peas.
As I said: pretty decent, if a bit tetchy and time-consuming.