1. Cook the manicotti shells according to package directions; drain. Preheat the oven to 400°F.
2. Thaw the spinach and squeeze dry. Peel and roughly chop the onion and garlic. Place in the bowl fitted with the ultrablade knife and mix at speed 11 for 10 seconds.
3. Add the oil and spinach. Launch the P1 simmer program at 270°F for 5 minutes.
4. At the end of the program, add egg, ricotta, nutmeg and 3⁄4 cup Parmesan. Season with salt and pepper. Mix at speed 9 for 30 seconds. Bring the mixture to the center using a spatula and mix for 30 seconds.
5. Fill the manicotti shells with the mixture and place in a 13 x 9-inch oven dish sprayed with nonstick cooking spray. In a medium bowl, combine cream, sour cream and remaining Parmesan; spread over manicotti. Bake for 30-35 minutes.