In a large skillet, warm 1/4 cup of olive oil over medium heat. Add the finely chopped onion and sauté for about 5–7 minutes, or until it becomes translucent and soft. Introduce the minced garlic and chopped fresh sage; continue to cook for an additional minute until fragrant.

Stir in the 15 ounces of pumpkin puree, allowing it to cook for 2–3 minutes.

Pour in 1/2 cup of heavy cream and add 1/4 cup of grated Parmesan cheese to the pumpkin mixture. Stir constantly for about 3–5 minutes until everything is smooth and melted together.

Sprinkle in salt, black pepper, and optional red pepper flakes to taste. Allow the sauce to simmer on low heat for 10-15 minutes.

While the sauce simmers, boil a large pot of salted water and cook 1 pound of pasta according to package directions until al dente. Reserve 1/2 cup of the pasta water before draining.

Add the drained pasta to the skillet with your pumpkin sauce. Toss gently but thoroughly to coat each piece of pasta.

If the sauce appears too thick, gradually add the reserved pasta water until you reach your desired consistency. Stir in half of the crumbled feta cheese.

To finish, drizzle 2 tablespoons of melted butter over the pasta. Serve garnished with remaining feta cheese and toasted pumpkin seeds.