Preheat your oven to 220°C (430°F).
Grease a deep-dish pizza pan or a cast-iron skillet with olive oil.
Press the proofed dough evenly into the bottom and up the sides of the pan to create a crust.
Layer half of the mozzarella cheese on the bottom of the crust.
Add the cooked Italian sausage, diced tomatoes, green bell pepper, onion, minced garlic, chopped basil, and 1 tsp dried oregano evenly over the cheese.
Season with salt and pepper.
Pour the prepared tomato sauce over the pizza toppings.
Sprinkle the remaining mozzarella cheese on top.
Place the pizza in the preheated oven and bake for 25-30 minutes or until the crust is golden brown and the cheese is bubbly and slightly browned.
Allow the pizza to cool for a few minutes before slicing.
Serve hot and enjoy your homemade Chicago-style pizza!