Prepare the Filling:

Cook sausage in a skillet until browned and crumbled. Drain excess fat.
If using, sauté bell pepper and onion in the same skillet until softened. Set aside.
Assemble the Pizza:

Preheat oven to 425°F (220°C). Grease a 9-inch or 10-inch deep-dish pizza pan.
Punch down dough and roll into a 12-inch circle.
Press dough into the pan, forming a thick crust.
Layer half of the mozzarella, then provolone, and finally Parmesan cheese.
Top with sausage, bell pepper, and onion (if using).
Pour tomato sauce over the filling.
Bake the Pizza:

Bake for 30-40 minutes, or until crust is golden brown and cheese is bubbly and melted.
If crust browns too quickly, cover edges with foil.
Cool and Serve:

Let the pizza cool for 5-10 minutes before slicing and serving.
Enjoy!