Step 1: Cook the Meat : In a skillet over medium heat, heat olive oil. Add ground beef or sausage and cook until browned. Add onion and garlic and cook until softened. Drain excess fat.

Step 2: Prepare the Ricotta Mixture : In a medium bowl, combine ricotta cheese, 1 cup of shredded mozzarella, Parmesan cheese, dried basil, oregano, salt, and pepper. Mix until smooth.

Step 3: Layer the Lasagna : Spray the slow cooker with nonstick cooking spray. Spread a thin layer of marinara sauce on the bottom. Place a layer of noodles over the sauce, breaking them to fit if necessary. Spread a portion of the ricotta mixture over the noodles, then a layer of meat mixture, followed by sauce. Repeat layers, ending with sauce on top. Sprinkle the remaining mozzarella cheese on top.

Step 4: Cook the Lasagna : Cover the slow cooker and cook on low for 4-5 hours or on high for 2-3 hours, until noodles are tender and cheese is melted and bubbly.

Step 5: Serve : Let the lasagna rest for 10-15 minutes before serving to allow it to set. Cut into portions and serve hot.