2 cups shredded cheese, like cheddar, monterey jack, or colby
1/2 teaspoon salt
2 teaspoons dijon mustard
In a large pot, over medium-high heat, bring water to a boil. Add the pasta and cook until al dente. Drain and set aside.
When the pasta has finished cooking, you can begin to prepare the cheese sauce. Start by warming 1 cup of the milk in a saucepan over medium heat. Whisk together the remaining 1/2 cup of milk and the 2 tablespoons of flour until there are no lumps. When you begin to see steam rising from the milk, whisk in the milk-and-flour mixture. Continue whisking until the milk thickens slightly to the consistency of heavy cream, 3-4 minutes.
Turning the heat to low, you can begin adding the shredded cheese into the milk. Stir in the salt and dijon mustard. Continue to stir until all the cheese has melted and the sauce is creamy. Taste and adjust the seasonings as desired. Remove the sauce from heat.
In a large serving bowl, combine the pasta and 1/2 of the cheese sauce. Stir to coat the pasta evenly. Add the second half of the sauce and any extra add-ins.
Serve the mac and cheese immediately while still warm. Leftovers will keep for up to a week and can be reheated. If the sauce is a little dry after re-heating, mix in a splash of milk to make it creamy again.
For a gluten free version, use gluten free pasta and an all purpose gluten free baking flour.