Heat a skillet over medium heat and cook the ground beef until browned and fully cooked.
Drain excess fat, then season the beef with salt, pepper, garlic powder, and Italian seasoning.
Lightly grease the inside of the slow cooker.
Spread a thin layer of pasta sauce on the bottom.
Add a layer of ravioli, followed by seasoned beef, sauce, mozzarella, and Parmesan.
Repeat layers until all ingredients are used, ending with sauce and cheese on top.
Cover and cook on LOW for 4–5 hours or HIGH for 2–3 hours, until bubbly and heated through.