Cook lasagna noodles in boiling water for 5 minutes, drain. In a skillet, brown the meat & onion, until onion is tender. Drain fat. Transfer meat mixture to Crock-Pot. Stir in tomatoes, tomato paste, bouillon & seasonings. Add cooked lasagna noodles. In a small bowl, mix melted butter, flour, salt, pepper, milk, and 1 cup of mozzarella cheese. Stir into Crock-Pot. Cover and cook on Low 4-6 hours or on High 2-3 hours. In the last 30 minutes, turn Crock-Pot to High, if cooking on Low. Top with remainder of mozzarella cheese. Serve when cheese is melted.