Instructions

1. Cook the Potatoes:

Place the cubed potatoes in a large pot of salted water. Bring to a boil and cook for 15-20 minutes, or until fork-tender. Drain well.

2. Make the Mashed Potatoes:

Return the drained potatoes to the pot. Add the butter, warm milk, salt, and pepper. Mash until smooth and creamy. Set aside.

3. Cook the Beef Filling:

While the potatoes are cooking, preheat your oven to 375°F (190°C).
In a large skillet, heat the olive oil over medium heat. Add the chopped onion and cook until softened, about 5 minutes. Add the minced garlic and cook for another minute until fragrant.
Add the ground beef, breaking it up with a spoon, and cook until browned. Drain off any excess fat.
Stir in the tomato paste and cook for 1 minute. Add the marinara sauce, Worcestershire sauce, paprika, salt, and pepper. Let it simmer for 5 minutes until slightly thickened.

4. Assemble the Casserole:

Spread the savory beef mixture evenly into the bottom of a 9×9 or similar-sized baking dish.
Carefully spoon the mashed potatoes over the beef layer. Use a fork to spread them evenly and create decorative peaks that will brown nicely.
Sprinkle the shredded mozzarella and Parmesan cheese (if using) over the top.

5. Bake and Serve:

Bake for 20-25 minutes, or until the cheese is melted and bubbly, and the edges are lightly browned.
For an extra golden top, you can broil for the last 1-2 minutes (watch closely!).
Let the casserole rest for 5-10 minutes before serving. This allows the layers to set for cleaner slices.