Boil the macaroni, strain and set aside.
In the same pan that the noodles were cooked in, add the butter and melt over medium heat.
Once the butter is melted, add the flour and whisk. Continue to whisk until the flour has turned a light golden color, about 2-4 minutes. Add the milk, whisking constantly until the mixture is thickened, about 2-3 minutes.
Add the cheese, crème fraiche and salt. Place the cooked macaroni into the cheese mixture. Stir to combine. Serve warm.