In a large skillet, heat olive oil over medium heat. Add the Italian sausage and cook until browned, breaking it apart with a spoon, about 5-7 minutes. Drain excess fat if necessary. Add diced onion and minced garlic, cooking until the onion is translucent, about 3-4 minutes. Season with salt and pepper. Remove from heat and set aside.

In a mixing bowl, combine ricotta cheese, grated Parmesan cheese, egg, and Italian seasoning. Mix until well blended and set aside.

Preheat your oven to 375°F (190°C).

In a 9x13-inch baking dish, spread a thin layer of Alfredo sauce on the bottom. Layer half of the ravioli over the sauce, followed by half of the sausage mixture, and half of the ricotta mixture. Sprinkle with one cup of mozzarella cheese.

Repeat the layers with the remaining ravioli, sausage, ricotta mixture, and top with the remaining Alfredo sauce. Finish with the remaining mozzarella cheese.

Cover the baking dish with aluminum foil and bake for 25 minutes. Remove the foil and bake for an additional 15 minutes, or until the cheese is bubbly and golden.

Let the lasagna cool for 10 minutes before slicing. Garnish with chopped parsley before serving.