In a medium bowl, combine 2 cups of all-purpose flour and a pinch of salt. Cut in 1 cup of cold unsalted butter using a pastry cutter until the mixture resembles coarse crumbs. Gradually add 4–6 tablespoons of cold water, mixing until the dough forms. Shape into a ball, wrap in plastic, and chill in the refrigerator for 30 minutes.

While the dough chills, heat 2 tablespoons of olive oil in a large skillet over medium heat. Add 1 pound of ground beef or Italian sausage, breaking it up until browned, about 5–7 minutes. Stir in diced onions, bell peppers, and mushrooms, cooking until softened, another 5 minutes. Drain excess grease if necessary.

To the browned meat and veggies, stir in 1 cup of marinara sauce and season with 1 teaspoon of Italian seasoning, ½ teaspoon of garlic powder, and black pepper to taste. Let the mixture simmer for 3–5 minutes, allowing the flavors to meld. Remove from heat and let it cool slightly before adding 2 cups of shredded mozzarella and ½ cup of grated Parmesan cheese.

Preheat your oven to 425°F (220°C). On a floured surface, roll out about two-thirds of the chilled dough to fit your deep-dish pie pan, about ¼ inch thick. Transfer the rolled-out dough into the pan, gently pressing it into the edges. Trim any overhang, but leave a bit for sealing.

Spoon the filling into the prepared crust, spreading it evenly. If desired, layer some sliced pepperoni on top for extra flavor. Roll out the remaining dough for the top crust, placing it carefully over the filling. Seal the edges by crimping them with your fingers or a fork, ensuring no filling escapes.

Make a few small slits in the top crust with a sharp knife to allow steam to escape during cooking. For a golden finish, beat 1 egg in a small bowl and brush the egg wash over the top crust.

Place the assembled Pizza Pot Pie in the preheated oven and bake for 15 minutes at 425°F (220°C). Afterward, reduce the oven temperature to 375°F (190°C) and continue baking for an additional 25–30 minutes, or until the crust is golden brown and filling bubbles slightly.

Once baked, remove the Pizza Pot Pie from the oven and let it rest for 10 minutes before slicing.