Brown the ground beef in a skillet and drain excess fat.
In a bowl, mix ricotta cheese, egg, Italian seasoning, salt, and pepper.
Spread a thin layer of marinara sauce at the bottom of the crockpot.
Place 3 lasagna noodles over the sauce, breaking them if necessary.
Layer half of the ricotta mixture over the noodles.
Add half of the ground beef on top of the ricotta layer.
Sprinkle a layer of mozzarella cheese over the beef.
Repeat the layers with remaining ingredients.
Cover and cook on low for 4-6 hours until noodles are tender.
Let it sit for 10-15 minutes before serving.