Preheat the oven to 375°F. Coat a lasagna dish with nonstick cooking spray. Cook the sausage and ground beef in a large skillet over medium-high heat until the meat is no longer pink and crumbles. Drain off the excess oil.
Set aside 2 cups of the marinara sauce. Stir the remaining marinara sauce into the meat mixture. Stir in the Italian seasoning and garlic powder.
Stir together the ricotta, eggs, basil, parsley, salt, pepper, and nutmeg in a medium bowl. Stir together the cheese in a separate medium bowl.
Spread 1 cup of the reserved marinara sauce in the bottom of the prepared lasagna dish until it covers the bottom. Place 3 lasagna noodles on the bottom of the dish in a single layer. Break a 4th noodle into smaller pieces to cover the remaining sauce.
Top the noodles with about 1 ½ cups of the meat mixture. Dollop a little less than 1 cup of the ricotta mixture over the meat mixture and spread gently to cover. Sprinkle with about ¾ cup of the cheese.
Repeat the layers until you use up all the meat mixture and ricotta cheese. Top with the remaining noodles. Spread the remaining 1 cup of marinara sauce over the noodles and sprinkle with the remaining cheese.
Tear off a piece of aluminum foil to cover the dish. Coat the underside of the foil with nonstick cooking spray and cover the dish tightly. Bake for 50 minutes or until the noodles are tender and the lasagna is bubbly.
Uncover and bake for 10 more minutes or until the cheese is browned. Remove the lasagna from the oven and let stand for 30 minutes before cutting into squares. Garnish with additional parsley, if desired.