Heat olive oil in a high-walled stainless steel sauté pan on medium-high heat.
Add sliced onions and a generous amount of salt to pan and cook for 5 minutes until caramelized. Add minced garlic and stir for 1 minute then add the jar of marinara sauce.
In a separate pan, cook meat until cooked through. Add to pan of marinara sauce and onions.
Spray a 7×9 Pyrex dish with Pam and spread a thin layer of sauce on the bottom of dish. Place the Four Cheese Manicotti or Cheese Ravioli on the sauce and then cover with remaining sauce.
Cover dish with foil and bake at 350ºF for 40 minutes until bubbly and hot. Uncover dish and sprinkle with mozzarella cheese, then bake uncovered for 5 minutes.