Cook the ground beef and Italian sausage in a skillet over medium heat until browned.
Add garlic and onion, cooking until softened.
Stir in the chopped tomatoes and oregano.
Let the sauce simmer for about 20 minutes, allowing the flavors to blend.
In a bowl, mix together the ricotta, egg, and half of the Parmesan cheese until well combined.
Preheat your oven to 375°F (190°C).
Start assembling the lasagna by spreading a layer of sauce in a 9 by 12-inch baking dish.
Lay down three lasagna noodles, followed by a layer of the cheese mixture and meat sauce.
Sprinkle some mozzarella on top.
Repeat the layers two more times.
Finish with a generous layer of mozzarella and remaining Parmesan on top.
Cover the dish with foil and bake for 30 minutes.
Remove the foil and bake for an additional 15 minutes until the cheese is golden and bubbling.