Cook the Meat: In a large skillet over medium heat, brown ground beef and Italian sausage for 5–7 minutes. Add diced onion and minced garlic, cooking until onion is translucent, about 2–3 minutes.

Prepare the Sauce: Incorporate marinara sauce and diced tomatoes into the meat mixture. Add Italian seasoning, salt, and pepper. Simmer on low heat for 15 minutes.

Make the Cheese Mixture: In a mixing bowl, combine ricotta or cottage cheese, cream cheese, and sour cream. Add egg and Parmesan, mixing until smooth.

Layer the Lasagna: Preheat oven to 375°F. In a greased baking dish, layer meat sauce, 3 lasagna noodles, and cheese mixture. Repeat layers twice and finish with remaining sauce and reserved mozzarella.

Bake the Lasagna: Cover with foil and bake for 25 minutes. Remove foil and bake for an additional 20 minutes until golden.

Rest and Serve: Let rest for 10–15 minutes before slicing. Garnish with parsley or Parmesan if desired.