Step 1

Bring a large pot of water to a boil for the pasta. Salt the water and add the pasta. Cook until 1 to 2 minutes shy of the package directions.

Step 2

Meanwhile, in a large skillet or medium pot, melt the butter over medium to medium-high heat. Whisk in the flour, then slowly whisk in the milk. Bring to a bubble. Cook, whisking often, until thick enough to coat the back of a spoon, about 2 minutes. Reduce heat to medium-low. Whisk in the pumpkin. Add the granulated garlic, dry mustard, cayenne, white pepper, and nutmeg; season with salt. Add the cheeses. Stir in a figure eight motion until the cheeses melt into the sauce, a minute or two.

Step 3

Scoop out 1/2 cup of the pasta cooking water. Drain the pasta. Add the pasta to the sauce. Add the cooking water a little at a time if the sauce is too thick. Top with the chives.