Cook the elbow macaroni according to the package instructions. Drain and set aside.
In a large saucepan, melt the butter over medium heat. Stir in the flour and cook for about 1 minute, stirring constantly.
Gradually whisk in the milk and cook, whisking constantly until the mixture is smooth and thickened.
Stir in the pumpkin puree, garlic powder, nutmeg, salt, and pepper. Cook until heated through.
Add the shredded cheddar cheese and stir until melted and smooth.
Add the cooked macaroni to the cheese sauce and stir until well coated.
Serve immediately and enjoy your Pumpkin Mac and Cheese!