Cook macaroni according to package instructions. Drain pasta about 1 minute before instructed; just slightly before pasta is al dente. Set aside.
Melt butter in a medium saucepan over medium-low heat. Whisk in flour and cook, whisking constantly, until golden in color; about 1-2 minutes. Whisk in thyme and paprika and cook for 1 minute. Whisk in milk/cream and bring to a gentle simmer. Do not boil. Simmer until thickened; about 5 minutes, whisking frequently.
Stir in salt, pepper, nutmeg and pumpkin purée until smooth.
Remove from heat and stir in cheeses until melted. Stir pasta and cheese sauce together in pan. Serve as is or bake as directed below.
To bake: Preheat oven to 350 degrees F. Spray an 11x7-inch baking dish with nonstick cooking spray. Pour pumpkin mac & cheese into the prepared baking dish. Sprinkle with breadcrumbs and bake in the preheated oven for 20-30 minutes, or until breadcrumbs are golden and cheese is bubbly (Optional: place under the broiler during the last few minutes for more browning, but be sure to watch closely!).
Cool for 5-10 minutes before serving.