Cook pasta in a large pot of boiling salt water until al dente (or slightly undercooked - see notes). Take out a scoop of pasta water, then drain pasta over a sieve.
Heat a skillet with olive oil. Add minced garlic and sage, sauté for 3 minutes until fragrant.
Mix dairy-free milk and cornstarch in a bowl and add it with the pumpkin puree to the skillet. Cook while stirring constantly until slightly thickened (approx. 5 minutes).
Season to taste with nutritional yeast (optional), salt, pepper, nutmeg, and cayenne pepper. → Feel free to add a pinch of ground cinnamon.
Add drained pasta and toss for one minute! Thin the sauce with pasta water if desired!