Cook the pasta to 'al dente' per the package instructions. Transfer to a strainer, run under cold water, and drain well. Add the pasta to a waiting mixing bowl, and set aside.
16 oz lasagna noodles
Add the beef, sausage, onion, and garlic to a large skillet set over medium heat. Cook and crumble until browned through. Strain to remove all excess grease, then return the meat mixture to the skillet.
1 lb ground beef, 1 lb ground sausage, 1 small sweet onion, 3 tsp minced garlic
Add the sauce, seasoning, and salt & pepper to the meat in the skillet. Stir to combine, and allow the sauce to simmer for 5 minutes.
1 28 oz jar marinara sauce, 1/2 tsp dried oregano, salt & pepper, pinch crushed red pepper flakes
In a mixing bowl combine the ricotta and spinach and stir together until evenly combined. Set aside.
2 1/2 cups ricotta cheese, 16 oz pkg frozen chopped spinach
Pour the meat sauce into the bowl with the drained pasta, stirring until evenly combined. Add one cup of mozzarella and one cup of Parmesan cheese, stirring again until evenly combined.
2 1/2 cups shredded mozzarella cheese, 2 cups shredded Parmesan cheese
Spray a 12x7" rimmed baking sheet with nonstick cooking spray, then spread the meat and pasta mixture evenly out in a single layer.
Add the ricotta mixture in dollops evenly out over the pasta until it's all been added. Sprinkle the remaining cheeses evenly out overtop.
Bake at 350° for 35-40 minutes. Carefully remove the hot pan from the oven, and let rest for 10 minutes.
Serve warm and enjoy!