Preheat oven to 350F. Grease a 9×13-inch baking dish. Cook the Italian sausage in a large skillet over medium heat, stirring occasionally until it is browned and cooked through (about 10 minutes). Drain any fat from the skillet.
In a medium bowl, mix together the ricotta cheese, egg, and parsley flakes. Spread 1/2 cup of the Prego pasta sauce into the bottom of the baking dish. Place 4 uncooked Creamette Lasagna noodles on top of the sauce.
Spread half of the ricotta mixture over each noodle, then spread all of the cooked sausages over the ricotta. Sprinkle 1/2 cup of Mozzarella and 1/4 cup of Parmesan cheese over the Italian sausage.
Place 4 more uncooked Creamette Lasagna noodles on top of the cheese layer, then spread with remaining Prego pasta sauce and top with remaining Mozzarella and Parmesan cheese.
Sprinkle the sugar, nutmeg, and ground black pepper over the cheese. Cover the baking dish with aluminum foil and bake for 30 minutes in preheated oven. Remove from oven and let sit covered for 10 minutes before serving.