HOW TO MAKE IT :
- In a saucepan over medium heat, melt the butter.
- Add the flour and whisk constantly for 1-2 minutes (or until the mixture turns light brown).
- Remove from heat and gradually pour in the warm milk, whisking constantly.
- Return the pan to the heat, whisk another 3-5 minutes or until thickened.
- Add the salt, garlic powder, ground mustard, and cayenne pepper and stir to combine. Remove from heat.
- Add the cheeses, stirring to melt.
- Pour the sauce over the top of the cooked elbow macaroni. Stir to combine.
- Season with salt and pepper, and top with chopped parsley.