1. In a medium saucepan over medium heat, add butter, and melt. Add garlic and cook for 30 seconds, stirring continuously. Add flour; cook 30 seconds stirring continuously. Add milk slowly, whisking constantly. Increase heat to medium high, and continue whisking.
When the liquid bubbles and thickens, remove from heat and add cheese, stirring until melted and combined. Add pumpkin, nutmeg, salt, and pepper; whisk to combine completely.
2. Pour sauce over cooked pasta and toss to combine. Garnish with parsley and cheese if desired.
Grab a fork and dig in!