Fit 1 piecrust into a 9" deep dish pieplate according to package directions; trim dough around edges of pieplate.
Place remaining piecrust on a lightly floured surface, cut desired shapes with a decorative 1" cookie cutter. Brush edge of piecrust in pieplate with beaten egg white; gently press dough shapes onto edge of piecrust. Pierce bottom and sides with a fork.
Line piecrust with parchment paper or aluminum foil; fill piecrust with pie weights or dried beans.
Bake at 400 for 10 minutes. Remove weights and parchment paper; bake 5 more minutes, and set aside. Reduce oven temperature to 350.
Cook bacon in a large skillet over medium high heat until crisp. Remove bacon, and drain on paper towels, reserving 2 t. drippings in pan. Crumble bacon and set aside.
Saute chopped onion and mushrooms in hot drippings 3 to 4 minutes or until tender.
Stir together bacon, onion mixture, half and half, and next 4 ingredients in a large bowl. Combine cheese and flour; add to bacon mixture, stirring until blended. Pour mixture into crust.
Bake at 350 for 45 to 50 minutes or until a wooden pick inserted in center comes out clean. Shield edges with aluminum foil to prevent excess browning, if necessary. Let stand 10 minutes before serving.