In a large pot over medium heat, melt the butter.
Add the garlic, sage, and thyme and cook until fragrant, about 2 to 3 minutes.
Remove the sage leaves and thyme sprigs and discard them.
Still over medium heat, pour in the chicken broth and stir in the pumpkin purée and heavy cream until smooth.
Season with mustard powder, onion powder, cayenne, smoked paprika, salt, and nutmeg.
Raise the heat to medium-high, add the pasta, and bring the mixture to a boil.
Reduce to a simmer and cook uncovered, stirring frequently, until the pasta is tender and most of the liquid has been absorbed, about 14 to 15 minutes.
Lower the heat to the lowest setting, add the cheeses, and gently fold them in with a rubber spatula until completely melted into the sauce.
Taste and adjust seasoning as needed.
Serve hot, garnished with parmesan and freshly cracked black pepper.
