01 -
Preheat the oven to 175°C (350°F) and move the rack to the top third of the oven. Prep the mozzarella and parmesan cheese.
02 -
Add olive oil and chopped onion to a skillet and sauté for 4-5 minutes over medium-high heat.
03 -
Add the ground beef and minced garlic. Cook, breaking the beef up with a spoon, until browned and cooked through (about 8 minutes). If there is excess fat, remove it. Season with a pinch of salt and pepper.
04 -
Stir 2 cups of marinara sauce into the cooked beef mixture and let it heat through.
05 -
Spread 1 cup of marinara sauce evenly on the bottom of a greased 23x33 cm (9x13 inch) baking dish. Add half of the ravioli in an even layer, followed by half of the beef mixture, and then half of the mozzarella and parmesan cheese. Repeat this layering process, finishing with a cheese layer.
06 -
Cover the dish with foil and bake for 30 minutes. Remove the foil and broil for a few minutes until the cheese is bubbly and browned. Serve immediately.