Step 1

Preheat your oven to 400 degrees F. Spray a 9 x 13 baking dish with cooking spray. Set aside.

Step 2

While oven is preheating, cook sausage and onions in a large skillet over medium high heat, crumbling sausage with a wooden spoon while it is cooking. Cook until sausage is browned, no longer pink and fully cooked (about 6 minutes).

Step 3

Add garlic and cook until fragrant (about 30 seconds), stirring constantly.

Step 4

Drain off excess fat.

Step 5

Add pasta sauce and drained diced tomatoes to sausage mixture and stir to combine. Remove from heat.

Step 6

Spread 1 cup of the meat sauce in the bottom of prepared baking dish.

Step 7

Arrange half of the ravioli over the meat sauce, then spread half of the remaining meat sauce over the ravioli (about 2 ¼ cup meat sauce).

Step 8

Evenly sprinkle half of the shredded cheese over the meat sauce.

Step 9

Repeat layers: Arrange the remaining half of the ravioli over cheese, spread the remaining meat sauce over ravioli, then sprinkle with remaining cheese.

Step 10

Cover with aluminum foil and bake for 30 minutes. Remove foil and bake for an additional 10 to 15 minutes, or until heated through and bubbling around edges.