Preheat the oven to 400°F (200°C) and line a 17” x 12” baking sheet with parchment paper. Spread 1½ cups of shredded mozzarella evenly over the sheet.
Arrange the potato slices slightly overlapping in rows until the surface is covered. Brush with olive oil, then sprinkle with salt, paprika, and onion powder. Bake for 20–25 minutes, or until tender.
While the potatoes bake, heat olive oil in a large pan. Sauté onion, green pepper, and red pepper for 3–4 minutes. Add garlic and cook for 30 seconds until fragrant.
Stir in ground lamb, breaking it up with a spoon until fully cooked. Drain excess fat, then mix in tomato paste, marinara, and seasonings. Let it simmer for 2–3 minutes and set aside.
Once the potato base is baked and slightly cooled, sprinkle another ½ cup mozzarella on top. Spread the filling evenly over it, then sprinkle with the remaining mozzarella. Starting from the short side, roll the potatoes tightly into a log, using parchment paper to guide you. Place seam side down on the sheet.
Top with the last sprinkle of cheese and bake for 7–10 minutes until golden and bubbly. Let rest for 5 minutes before slicing thick rounds. Serve warm and enjoy the crispy, cheesy goodness.