01 -
Bring a pot of salted water to a boil and cook the pasta according to package directions until al dente. Drain well and set aside.
02 -
In the same pot used for pasta (or a separate one if you prefer), melt 2 tablespoons of butter over medium heat. Once completely melted, sprinkle in the flour and whisk continuously for about 1 minute until the mixture is smooth and no clumps remain - this creates your roux.
03 -
Slowly pour in the heavy cream while continuing to whisk, creating a smooth base. Break up the Boursin cheese into chunks and add to the pot along with the freshly grated white cheddar. Stir constantly until all the cheese has melted and the sauce is velvety smooth.
04 -
If the sauce seems too thick (it will thicken further as it sits with the pasta), gradually add milk until you reach your desired creaminess. I typically add about 1/2 cup. Season with salt to taste.
05 -
Add the drained pasta to the pot with the cheese sauce and gently fold everything together until the pasta is completely coated. Meanwhile, for the optional topping, melt the remaining 2 tablespoons of butter in a small pan, add the breadcrumbs, and toast until golden brown. Sprinkle the toasted breadcrumbs over individual servings of mac and cheese for a delightful crunch.