Preheat oven to 350°F. Spray 8x8-inch baking dish with cooking spray; set aside. Cook pasta according to package directions.
Brown meat with onions in large skillet over medium-high heat while pasta is cooking, stirring occasionally to break up the meat. Drain. Add diced tomatoes with their sauce, the tomato paste, water, parsley, salt and black pepper; mix well. Reduce heat to medium-low; simmer 5 minutes, stirring occasionally.
Drain pasta. Add to tomato mixture along with the Parmesan cheese and crushed red pepper; mix well. Spoon into prepared baking dish. Sprinkle with mozzarella cheese.
Bake 20 minutes, or until pasta mixture is hot and bubbly and cheese is melted. Let stand 10 minutes before serving.