Heat the butter in a wide, shallow pan over medium heat. Add the onion and cook for a few minutes until translucent, about 3 minutes. Add the garlic and cook 1 minute more. Add wine and the sliced mushrooms. Cook until browned, stirring frequently. The mushrooms may crowd the pan, but they will shrink as they cook. Season with salt and pepper.
While the mushrooms are cooking, roll out one disk of the pie dough into a rough 13-inch circle on a lightly floured surface. Transfer the dough to a 9-inch pie dish.
In bowl, whisk together the heavy cream, eggs, and flour. Add the mushroom mixture, herbs, and cheese and stir to combine. Dump mixture into the bottom pie crust.
Roll out the second dough disk and transfer it to the top of the pie. Pinch the two crusts together and tuck into the dish to seal. Cut slits into the crust as vents. Brush pie with egg wash.
Bake at 350 degrees F on the bottom rack of your oven until crust is golden brown and juices are bubbling, about 60-75 minutes. For best results, let pie cool to room temperature before serving to let the filling thicken properly. (I let it sit about 30 minutes which worked just fine)
If you desire you can store prebaked pie in the refrigerator then reheat pie at 350 degrees F for 30 minutes when ready to serve.
**The origional recipe can be found
here which includes
this parmasan pie crust. I have included them on my page as seperate entries as I love this crust with many savory pies. Plain pie crust works with the mushroom pie as well.