Set a large skillet over medium heat and allow it to get hot, then spray it down with non-stick cooking spray. Add onion and sauté 1-2 minutes, until tender. Add garlic, ground turkey, salt, pepper, and Italian seasoning and cook meat until browned.
Add canned pumpkin, cinnamon, and nutmeg and stir thoroughly before adding tomato paste. Stir again, drop heat to low, cover and allow to simmer.
In a bowl, combine ricotta cheese, Parmesan cheese, Italian seasoning, salt, and pepper. Mix thoroughly.
To assemble ravioli, lay out two zucchini slices in the shape of a plus sign. Drop a generous portion of the ricotta into the center, then fold the very bottom slice of zucchini first, followed by the top one. Lay it upside down in an 8 x 8 casserole dish.
When each ravioli is finished, top with pumpkin/meat sauce and bake for 30 minutes. Top with additional cheese, if desired.