Preheat oven to 350 degrees F (180 degrees C). Lightly grease a 3 quart baking dish with cooking spray. Spread about ½ cup sauce on the bottom of the dish and arrange half of the ravioli in a single layer over the sauce.
Top with cooked sausage, spinach, and sundried tomatoes. Pour 1 ½ cups of alfredo sauce over the spinach mixture. Sprinkle with half of the mozzarella and Parmesan cheese and top with the remaining ravioli in a single layer.
Pour over remaining sauce and top with remaining mozzarella and Parmesan cheeses.
Cover and bake for about 1 hour, uncovering during the last 15 minutes, until golden brown around the edges and bubbly. Let stand 10 minutes before serving.
