In a pan, heat olive oil on medium, then sauté onions until softened. Add minced garlic and cook until fragrant. Stir in ground beef and sausage, crumbling them as they cook until browned.

Pour in marinara sauce and sprinkle Italian seasoning. Let it simmer for 30 minutes, stirring occasionally. Season with salt and pepper to taste, then set the meat sauce aside.

In a separate bowl, combine ricotta cheese, ½ cup Parmesan, parsley, eggs, and a pinch of salt and pepper. Stir until the mixture is well blended.

Grease the inside of your slow cooker and start with 1 cup of meat sauce spread at the bottom. Add a layer of uncooked lasagna noodles, cutting them to fit the shape of the slow cooker.

Spoon a portion of the ricotta mixture over the noodles, then add mozzarella and a sprinkle of Parmesan. Repeat the layering—sauce, noodles, ricotta, and cheeses—three more times.

Top with the remaining mozzarella and Parmesan. Set the slow cooker to low heat and cook for about 7 hours, until the lasagna is bubbling and the noodles are tender.

Let the lasagna rest in the slow cooker on the warm setting for at least 15 minutes before slicing and serving. For an extra touch, serve with additional meat sauce and a sprinkle of Parmesan.