Heat olive oil in a large skillet over medium heat. Add the ground beef or mild Italian sausage and chopped onion, then cook for 6–8 minutes, breaking up the meat until browned and the onion is soft.

Add the minced garlic and cook for about 30 seconds, stirring constantly so it becomes fragrant without browning.

Stir in the marinara sauce, Alfredo sauce, heavy cream or whole milk, Italian seasoning, salt, black pepper, and optional red pepper flakes. Simmer gently for 8–10 minutes, avoiding an aggressive boil.

While the sauce simmers, combine ricotta, egg, Parmesan, parsley, salt, and black pepper in a bowl. Stir until evenly blended.

Cook regular lasagna noodles until just al dente according to the package directions. Drain and lay them flat so they do not stick together; oven-ready noodles can be used without boiling.

Grease a 9 x 13-inch baking dish and spread about 1 cup of rosa sauce across the bottom. This first layer helps keep the noodles tender and prevents sticking.

Add 3–4 noodles, about one-third of the remaining sauce, one-third of the ricotta mixture, and about 1 cup of mozzarella. Spread each layer as evenly as possible.

Repeat the noodle, sauce, ricotta, and mozzarella layers twice more. Finish with the remaining sauce, the remaining mozzarella, and 1/4 cup Parmesan.

Cover the baking dish tightly with aluminum foil and bake at 375°F (190°C) for 25–30 minutes. Keeping the dish covered helps the center cook evenly and prevents the noodles from drying.

Remove the foil and bake for another 15–20 minutes, until the cheese is melted, bubbling, and lightly browned. Watch the top during the final minutes so the cheese reaches a rich golden color.

Let the lasagna rest for 10–15 minutes before slicing. This short pause allows the layers to set, making cleaner portions with less sauce running onto the plate.