Prepare pasta according to package directions. Drain and set aside in large bowl.

Preheat the oven to 400° F.

Spray a non-stick skillet with vegetable oil cooking spray. Heat oil over medium heat. Add onions and sauté until tender, about 5 minutes. Add garlic and sauté 1 more minute. Remove from heat. Stir in tomatoes.

Place ricotta cheese, 1 1/2 cups of the mozzarella cheese, 2 tbsp. of the Parmesan cheese and milk in a food processor or blender. Process until smooth.

Add the tomato and cheese mixtures, parsley, basil and pepper to the cooked pasta. Toss well to combine.

Spray a 2 1/2 to 3 quart (an 8 or 9 x 12-inch oblong dish works well) baking dish with vegetable spray. Spoon the pasta mixture into the dish. Sprinkle with remaining 1/2 cup mozzarella and 2 tbsp. Parmesan cheeses.

Bake at 400° F for 20 minutes, or until lightly browned.