Heat the olive oil in a large pot or Dutch oven over medium heat. Add the sausage, onion, sage, rosemary, nutmeg, salt, and black pepper.
Cook for 5 to 7 minutes, breaking the meat apart with a spoon. The sausage is safe to eat when it reaches an internal temperature of 160°F (71°C) and the onions are soft.
Stir in the minced garlic and cook for 30 seconds until fragrant.
Pour in the white wine to deglaze the pot. Scrape up any browned bits from the bottom with a wooden spoon.
Add the pasta, pumpkin puree, and chicken broth. Press the pasta down gently so it is mostly submerged in the liquid.
Increase the heat to high and bring the mixture to a boil. Once boiling, reduce the heat to medium-low to maintain a steady simmer.
Cook for 9 to 12 minutes, stirring frequently so the pasta does not stick to the bottom. Cook until the pasta is tender and the liquid is mostly absorbed. Add another 1/4 cup (60 ml) of broth if the pan gets too dry before the pasta finishes.
Remove the pot from the heat. Stir in the ricotta cheese and chopped spinach until the spinach wilts and the sauce is smooth. Serve warm.