For meat filling, in a large skillet cook Italian sausage and onion until meat is brown and onion is tender. Drain fat. Pat with paper towels to remove additional fat. Stir in pizza sauce, mushrooms, pepperoni, basil, oregano, and red pepper.
For crust, on a lightly floured surface roll two-thirds of the bread dough into a 12-inch circle. (If necessary, let dough rest once or twice during rolling.) Carefully place the circle in a greased 9-inch springform pan, pressing the dough 1-1/2 inches up the sides. Sprinkle bottom of the dough with 1/2 cup of the mozzarella cheese. Spoon meat filling over cheese.
Pat spinach dry with paper towels. Mix spinach, egg, and remaining mozzarella cheese. Spread spinach mixture over meat filling.
Roll remaining dough into a 10-inch circle on a lightly floured surface.
Cut circle into 10 to 12 wedges. Arrange wedges atop spinach mixture, slightly overlapping edges and sealing ends to bottom crust along edge of pan. Brush top with melted margarine or butter and sprinkle with Parmesan or Romano cheese.
Bake in a 375 degree F oven for 40 to 45 minutes or until filling is hot and bread is done. If necessary, cover with foil the last 10 minutes of baking to prevent overbrowning. Cool on a wire rack for 10 minutes. Remove sides of springform pan. Cut into wedges. Makes 8 servings.