Preheat your oven to 190°C (375°F). Grease a 9x13-inch baking dish with olive oil or butter.

In a large skillet over medium heat, pour in olive oil and add chopped onion, sautéing until translucent, about 5 minutes. Add minced garlic and cook for another minute.

Add ground beef and Italian sausage to the skillet, cooking until browned, approximately 7-10 minutes. Drain excess fat.

Stir in crushed tomatoes, tomato paste, sugar, dried basil, Italian seasoning, salt, and pepper. Simmer on low for 20-25 minutes, stirring occasionally.

In a mixing bowl, combine ricotta, sour cream, egg, Parmesan cheese, and chopped parsley until smooth.

In the greased baking dish, spread half of the meat sauce, followed by half of the lasagna noodles, half of the ricotta mixture, and a sprinkle of mozzarella. Repeat layers, ending with meat sauce and mozzarella on top.

Cover with aluminum foil and bake for 30 minutes. Remove foil and bake for an additional 15-20 minutes until golden and bubbly.

Let the lasagna rest for about 15 minutes before slicing to set the layers.