Brown the sausage: In a large skillet over medium heat, cook the ground Italian sausage until browned and cooked through. Drain excess fat if necessary.

Sauté the veggies: Add chopped onion, minced garlic, bell pepper, and mushrooms (if using) to the skillet and sauté for about 5-7 minutes until softened.

Add pizza sauce: Stir in pizza sauce, Italian seasoning, salt, and pepper. Allow to simmer until heated through.

Incorporate cheese and toppings: Remove from heat, stir in shredded mozzarella, pepperoni, and olives (if using) until cheese melts.

Preheat the oven: Set oven to 400°F (200°C) for a crispy crust.

Prepare the dough: Roll out pizza dough on a floured surface to fit the skillet.

Assemble the pot pie: Pour filling into skillet, drape rolled-out dough over, tucking edges around the skillet.

Egg wash and seasoning: Brush dough with beaten egg and sprinkle with dried oregano.

Bake to perfection: Bake in the oven for 20-25 minutes until crust is golden brown.

Cool and serve: Let cool for 5 minutes before slicing.

Slice and enjoy: Cut into wedges and serve warm.