Step 1

In a large stockpot, cook the pasta in salted water according to the package directions. Drain well and set aside.

Step 2

Meanwhile, in a large pot, melt the butter over medium heat until it's bubbly and melted, about 2 minutes.

Step 3

Add the flour and cook, stirring constantly, until the roux is frothy and smells nutty, about 3 to 5 minutes.

Step 4

Slowly whisk in the milk and heavy cream. Add the Dijon mustard and bring the mixture to a simmer over medium heat. Cook for 10 minutes, until the liquid has thickened.

Step 5

Remove the pot from the heat and add the white cheddar cheese one handful at a time, stirring until it's melted before adding the next handful of cheese. When all the cheese is added and incorporated, stir in the salt and pepper.

Step 6

Add the cooked pasta to the cheese sauce and stir to combine. If the pasta cooled down while you were waiting for the cheese sauce to cook, simmer the mixture over medium-low heat until it's warmed through.

Step 7

If the cheese sauce is too thick, add a splash of milk to thin it out. Alternatively, if the sauce is too thin, simmer it gently with the pasta until it reaches the desired level of thickness.

Step 8

Serve immediately. If there are leftovers, add 1/2 cup milk when reheating the leftovers to loosen up the sauce.