Preheat oven to 375. Combine ingredients for the pie crust into a food processor or stand mixer. Mix until the dough forms a ball. Cut the dough in half and form two flat discs. Place in saran wrap and put in the refrigerator for at least an hour. When the dough is ready- roll out one disc onto a floured surface. (Can freeze the other). Place the dough into a 9-inch pie pan. Crimp edges. Fit a piece of parchment paper in the center of the crust and fill with dried beans or rice. Bake in the oven for 10 minutes. Remove the crust from the oven. Remove the parchment paper and dried beans or rice. Prick the crust(both bottom and sides) with a fork to allow steam and air bubbles to release. Place the crust back in the oven for 6 minutes. While cooling slightly, brown the sausage. Place in a bowl and set aside. Add the mushrooms to the same pan and saute for 5 minutes. Add eggs, half and half, salt and pepper, dill, and cheese to a large mixing bowl. Mix well. Place sausage, mushrooms, and scallions into the bottom of the crust. Pour in the egg mixture. Bake for 40 minutes or until a toothpick inserted into the center comes out clean.