Preheat your oven to 375°F (190°C). If you are using store-bought pie dough, allow it to soften for about 10 minutes, then press it into a deep-dish pan. Prick the bottom with a fork and pre-bake for 10 minutes until it is lightly golden.
In a large skillet, heat a tablespoon of olive oil over medium heat. Add the ground beef and sausage, seasoning with salt, pepper, garlic powder, and Italian seasoning. Sauté until the meat is browned, which should take about 7–10 minutes.
Spread a thin layer of pizza sauce over the pre-baked crust. Layer mozzarella cheese on top, followed by the meat mixture. Spoon another layer of pizza sauce and add more mozzarella cheese, then scatter the pepperoni and sprinkle with Parmesan.
Place the pie in the oven and bake for 25–30 minutes until the cheese is bubbly and golden brown.
Remove the pie from the oven and let it cool for 5–10 minutes before garnishing with fresh parsley and serving.