Cook pasta according to package instructions. Drain and set aside.

While the pasta cooks, melt butter in a skillet over medium-low heat. Add garlic and cook for about 1 minute until fragrant.

Reduce heat to low, add the heavy cream, and bring to a gentle simmer, whisking occasionally until it begins to thicken.

Stir in the salt, pepper, nutmeg, and Parmesan. Whisk until cheese is fully melted and incorporated.

Add the pumpkin puree and stir until smooth and creamy.

Toss the cooked pasta with the sauce until evenly coated.

Garnish with fresh sage, if desired, and serve warm.