heat oven to 400°F Coat an 8-cup casserole dish with cooking spray.
Slice each tube of polenta into 9 rounds. Arrange 9 rounds in a single layer over the bottom of the baking dish. Set aside.
In a medium bowl, mix together ricotta cheese, 1 cup of the mozzarella, garlic powder, pepper and egg. Spread mixture in an even layer over polenta.
In a small bowl, mix together pasta sauce, and chopped sausage. Spread half of the mixture over cheese. Arrange remaining 9 rounds of polenta in a single layer over sauce, then top with remaining sauce.
Sprinkle with Parmesan cheese and remaining 1 cup mozzarella cheese over sauce. Spray a sheet of foil with cooking spray, then use it to cover lasagna and bake for 20 minutes.
Remove foil, and bake for another 15 minutes, or until cheese is lightly browned. let stand for 5 minutes before serving.