Use a 12-inch nonstick skillet with a tight-fitting lid for this recipe.
1. Pour tomatoes with their juices into a 1-quart liquid measuring cup. Add water until mixture measures 1 quart.
2. Heat oil in large nonstick skillet over medium heat until shimmering. Add onion and 1/2 teaspoon salt and cook until onion begins to brown, about 5 minutes. Stir in garlic and pepper flakes and cook until fragrant, about 30 seconds. Add ground meat and cook, breaking apart meat, until no longer pink, about 4 minutes.
3. Scatter pasta over meat but do not stir. Pour diced tomatoes with juices and tomato sauce over pasta. Cover and bring to simmer. Reduce heat to medium-low and simmer, stirring occasionally, until pasta is tender, about 20 minutes.
4. Remove skillet from heat and stir in 1/2 cup Parmesan. Season with salt and pepper. Dot with heaping tablespoons ricotta, cover, and let stand off heat for 5 minutes. Sprinkle with basil and remaining 2 tablespoons Parmesan. Serve.
To make skillet lasagna with sausage and peppers:
Follow the recipe for skillet lasagna, substituting 1 pound Italian sausage, removed from its casing, for meatloaf mix. Add 1 chopped red bell pepper to skillet with onion in step 2.