Baked rice and potato casserole from southern Italy with tomatoes and cheese is golden comfort. This vegetarian mediterranean family dish is hearty, budget-friendly, and satisfying.
Preheat your oven to 375°F (190°C) and grease a 9x13-inch baking dish with 1 tbsp olive oil.
Peel and thinly slice the potatoes (about ⅛ inch thick) and the onion. Slice the tomatoes into rounds and mozzarella into thin slices.
Scatter half the sliced potatoes evenly in the prepared dish, season with a pinch of salt, pepper, and oregano, then layer half of the onions and tomatoes on top.
Spread the uncooked Arborio rice evenly over the vegetables, then drizzle with the remaining 1 tbsp olive oil.
Layer the remaining potatoes, onion, and tomatoes over the rice, season again, then top with mozzarella and Parmigiano-Reggiano cheese.
Pour 2 cups hot water (or vegetable broth) gently over the casserole, cover tightly with foil, and bake for 40 minutes.
Remove the foil and bake for an additional 30–35 minutes until the top is golden and most liquid is absorbed. Let rest 10 minutes before slicing and serving.