Preheat oven to 350 degrees F. Mist a 9 x 13-inch baking dish with nonstick spray and set aside.
Bring a large pot of water to a boil over high heat. Add pasta and cook until almost al dente, about 8-9 minutes. Drain pasta and return to pot.
In the meanwhile, heat oil in a large saucepan over medium heat. Once hot, add sausage and cook, breaking up with a wooden spoon until no longer pink; transfer to the pot with the cooked pasta and discard all but 1 tablespoon of liquid from the skillet.
Return skillet to heat and add onion and mushrooms; sauté until softened, approximately 4-5 minutes. Season with ¼ teaspoon salt and pepper. Add garlic and cook until fragrant, about 30 seconds. Add kale and cook for 5-7 minutes, or until wilted. Pour in wine and cook until reduced; transfer to the pot with the pasta and return to skillet to heat.
Pour half and half into skillet and bring to a simmer; reduce heat to medium-low and allow to simmer for 4-5 minutes until slightly thickened. Whisk in the pumpkin, ricotta, and remaining ¼ teaspoon salt and pepper
Add the pumpkin mixture to the pot with 1¼ cups of the mozzarella cheese; mix thoroughly and trasnfer to the prepared 9 x 13. Top with remaining ¾ cup mozzarella, cover with foil, and bake for 20-25 minutes, removing the foil 5 minutes before done baking. Serve hot.