This is my go-to favourite way to make macaroni and cheese at home. And with the leftovers? Top it with grated cheddar and heat it in the oven; delicious.
Cook the pasta according to the package instructions.
Meanwhile, in a medium heavy bottomed saucepan, melt the butter. Remove from heat, and whisk in the flour until completely combined.
Pour a little bit of the milk into the butter/flour mixture in several small additions, whisking each time, until the mixture becomes a smooth paste. Continue adding the rest of the milk until fully incorporated and smooth.
Add the salt and pepper, and place over medium-low heat, whisking constantly (to prevent burning), until the mixture becomes very hot.
Whisk in the cheese until completely melted, incorporated, and smooth. Add more salt if desired (the amount in the recipe should be enough).
Ladle over cooked pasta and serve.