Combine cheeses in large bowl, reserving some mozzarella. Brown meat with onion, garlic and oregano or Italian seasoning. Drain and return to pan. Add tomato sauce and tomato paste. Stir well and heat through. Spray interior of slow cooker. Place a small layer of meat and sauce mixture on bottom. Cover with dry pasta. Add several spoons of cheese mixture, spread over pasta. Add a layer of sauce, a layer of pasta, a layer of cheese. Repeat until all ingredients are gone. Cook on low 6 hours. Ten minutes before serving, sprinkle reserved mozzarella on top and allow cheese to melt.