Heat a large heavy saucepan over medium heat. Add oil, and brown the beef and the sausage. Drain excess water. Add the tomatoes, pepperoni, oregano, onions, garlic, 2 cups water, and season with salt and pepper. Simmer uncovered for 30 minutes.
Cook the noodles according to package directions. Do not overcooked.
Preheat oven to 350 degrees F.
Spoon some sauce in a 9x13 inch baking pan. Top with lasagna noodles then ricotta cheese. Sprinkle mozzarella cheese and parmesan. Repeat, ending with sauce and cheeses.
Bake for 40 minutes or until slightly brown and bubbly. Let stand for 10 minutes before serving.
Recipe by The Gluten Free at https://www.theglutenfree.com/gluten-free-cowboy-lasagna/