In a small bowl, mix together the onion powder, garlic powder, and oregano.
Spray a large slow cooker with non-stick spray. Pour half of one of the jars of spaghetti sauce in the slow cooker and place 2 1/2 lasagna noodles over the sauce. Spread about one cup of ricotta cheese over the noodles, then sprinkle 1/3 of the seasoning mixture over the ricotta layer. Sprinkle 1/4 cup of Parmesan over top. Repeat for 3 layers, ending with the remaining Parmesan cheese.
Put the lid on top and cook on LOW for 4-5 hours, or until the noodles are tender. Check frequently to keep the noodles from overcooking. Serve and enjoy!