Preheat the oven to 375 degrees F and lightly coat a 9 x 13-inch baking dish with cooking spray.
Bring a large pot of water to a boil, add the rigatoni, and cook until al dente. Drain and return the rigatoni to the pot.
While the rigatoni is cooking, combine the ricotta, pumpkin, eggs, and yogurt in a large bowl. Add the salt, pepper, and nutmeg. Pour the sauce over the pasta and coat completely.
Pour into the baking dish and top with the Parmesan cheese and pecans. Bake for 30 minutes. Top with the sage leaves and serve.
