Add the ground beef and cook until browned. Season with salt and pepper to taste. Remove from heat and let cool slightly.
Mix the Filling:
In a large bowl, combine the cooked meat mixture with the mashed potatoes. Stir in the Parmesan, breadcrumbs, beaten eggs, and milk until well incorporated. Optionally, you can add some shredded mozzarella or provolone for a cheesy center.
Assemble the Pie:
Preheat your oven to 350°F (175°C). Grease a 9-inch (23cm) pie dish or baking pan with olive oil.
Spread the meat and potato mixture evenly in the dish, pressing it down slightly to compact.
Bake:
Bake for about 30-40 minutes, or until the top is golden and the pie is set.
Serve:
Let the pie cool for a few minutes before slicing. Garnish with fresh parsley and serve warm.
