1Preheat oven to 425 degrees. In a large bowl, combine oil, garlic, salt and pepper. Add potatoes and toss to coat. Spread in an ungreased 15 by 10 inch baking pan. Cover tightly with foil. Bake for 35 to 40 minutes, or until tender. Let cool for 15 minutes. Reduce oven to 350 degrees.
In a large skillet, brown beef with onions and seasonings; drain well. Add pasta sauce and simmer on low for about 10 minutes. Stir together ricotta and spinach. Arrange 1/3 of potatoes evenly in a greased 9 by 13 inch baking dish. Layer with 1/2 of spinach mixture, 1/3 of meat sauce and 1/3 of mozzarella. Repeat the next layer with 1/2 of spinach mixture, 1/3 of meat sauce and 1/3 of mozzarella. Top with remaining potatoes, meat sauce and mozzarella. Sprinkle with parmesan cheese.
Bake uncovered for 35 to 40 minutes or until bubbly. Let stand for 5 minutes before serving.
Makes 8 to 10 servings.