I use a mild curry when i make them. Thicken the gravy with instant mashed taters or potato starch. Idahoan brand Instant mashed works really well actually. Get all the filling sauteed, cooked and thickened. Place the bottom crust in the greased pie pan and bake first for about 10min. Then add your filling after its cooled a bit and add the top crust. Some egg wash on the top crust is nice too.
You can skip partially browning the bottom first but it does turn out a little better if you do. More or less just easier to get the bottom cooked without burning the top is all.