Spray the crock of a slow cooker with non-stick cooking spray.
In a skillet set over medium-high heat, brown the ground beef, onion, garlic, Italian seasoning, and salt for 5 minutes, until onions are softened.
1 lb. ground beef, ½ cup onion, 4 cloves garlic, 1 teaspoon Italian seasoning, ½ teaspoon salt
Stir in the marinara sauce and ½ cup of water, then simmer for 5 minutes.
24 ounces marinara sauce, 1 cup water
Meanwhile, in a large bowl, combine the ricotta cheese, 1 cup mozzarella cheese, parmesan cheese, egg, basil, and pepper.
15 ounces ricotta cheese, 2 ½ cups shredded mozzarella cheese, ½ cup parmesan cheese, 1 egg, 1 teaspoon dried basil, ½ teaspoon black pepper
Evenly spread 1 cup of the meat sauce on the bottom of the crock, then top with 3 noodles, breaking them to fit. Gently spread a third of the cheese mixture on top of the noodles.
9-12 lasagna noodles
Repeat two more times, beginning with sauce and ending with cheese, creating 3 layers. Sprinkle the remaining mozzarella cheese on top.
Cover and cook on low for 4 hours, until noodles are tender. Top with fresh basil, if desired.
Fresh basil for garnish