01 - Preheat your oven to 400°F (200°C). Generously grease four 8–10 oz (240–300 ml) oven-safe ramekins or a deep 9-inch (23 cm) pie dish.
02 - Carefully line the bottom and sides of each prepared ramekin or pie dish with overlapping slices of pepperoni, forming a complete pepperoni 'crust.'
03 - In a mixing bowl, combine the sliced mushrooms, diced bell pepper, sliced black olives, crumbled Italian sausage (if using), dried oregano, garlic powder, and crushed red pepper flakes. Season with salt and freshly ground black pepper to your preference.
04 - Spoon 2–3 tablespoons of pizza sauce into the base of each ramekin (or spread approximately 1/2 cup into the pie dish). Follow with a layer of shredded mozzarella cheese, then add the prepared vegetable and sausage mixture. Crown with another layer of mozzarella cheese. Finally, top with the remaining pizza sauce and sprinkle evenly with grated Parmesan cheese.
05 - Unroll the pizza dough and cut circles slightly larger than the openings of your baking dishes. Place these dough circles over the filling in each dish, ensuring the edges are pressed to create a seal. Make small slits in the center of each dough circle to allow steam to escape during baking.
06 - Bake for 30–35 minutes, or until the pizza dough achieves a golden brown hue and is thoroughly cooked. Allow the pot pies to cool for 5 minutes before serving. Gently invert onto serving plates so the pepperoni crust is presented on top, or serve directly from the baking dishes.