Boil water in a large pot and cook the macaroni pasta according to package directions until al dente. Drain and set aside.

In the same pot, melt the butter over medium heat. Whisk in the all-purpose flour and cook for 1 minute to form a roux.

Slowly pour in the whole milk while whisking constantly to prevent lumps. Simmer for 3 to 4 minutes until the mixture thickens slightly.

Remove the pot from the heat. Stir in the sharp cheddar cheese, gruyere cheese, salt, and black pepper until completely melted and smooth.

Fold the cooked macaroni pasta into the cheese sauce until evenly coated.

Garnish with finely chopped fresh chives before serving.