Combine spinach, cheese, Canadian bacon, oregano, garlic and mushrooms for stuffing mixture. Spread dough in a greased deep-dish pan and up the sides for the bottom crust (approximately 16 ounces of dough for 14-inch deep-dish). Par-bake the crust for four minutes.
Add stuffing mixture to bottom crust in deep-dish pan and cover with top crust (approximately 13 ounces dough). Seal the two dough edges together with fingers and trim excess. Slit the top crust to allow steam to vent during baking. Add tomato sauce topping and bake in preheated 450 degree F oven on lower rack or directly on the pizza stone for 45 minutes or until crust is golden brown.
Remove from pan and cool 5 minutes on a wire rack before cutting and serving.
Alternate Stuffing Mixture
8 ounces shredded mozzarella cheese
1/4 cup shredded parmesan cheese
1/4 pound hot Italian sausage, browned/crumbled and drained
1/3 cup small pepperoni pieces
1/4 cup sliced black olives
1/4 cup sliced green olives
1/2 package frozen chopped spinach, thawed and drained
1 teaspoon oregano
1 tablespoon chopped parsley