Summarize this article in one sentence.
The quality of your ingredients can affect the quality of your cheese sauce. Start with a sharp cheddar cheese, shredded or in a block. If the cheese comes in a block, use a grater to make 2 cups of shredded cheese.  You can substitute cheddar cheese with other cheeses such as Gouda, or Swiss cheese. To spice up the basic sauce, add salsa, hot sauce, beer, or wine for a little extra flavor. In a saucepan over medium heat, slowly heat the butter for your cheese sauce. Keep an eye on the butter as it melts. You don’t want the butter to brown or turn a dark, burnt color, as this will change the flavor of your sauce. Slowly add the flour to the butter, blending evenly with a whisk. Then, add flour and mix until flour is completely blended with butter. Allow the mixture to cook for several minutes, until it just begins to change color slightly.  Be careful not to burn the mixture, as it will make your cheese sauce taste burnt. Slowly pour in the milk, stirring constantly until the mixture gets thick. Try to avoid lumps in the mixture. Pouring the milk slowly and stirring constantly will help you avoid lumps. Add 1 teaspoon salt, pepper, cayenne pepper, or other spices such as dried rosemary or thyme. Get creative and amp up the flavor of your cheese sauce. Start with 1 teaspoon of your chosen spice. You can adjust the sauce to taste once you add in the cheese. Use caution when adding salt. Too much salt is difficult to remove, and many cheeses have a high salt content already. The sauce may also have salt in it already if you used salted butter. Removing the sauce from the heat before you add the shredded cheese will prevent the sauce from separating or curdling. Add the shredded cheese one handful at a time. Stir the sauce with a spoon and allow the cheese to melt each time before adding more cheese. The cheese sauce may harden as it cools, so serve it right away, drizzled over chips, on a baked potato, or over steamed vegetables. It should keep for up to three days. Don’t reheat leftover sauce over high heat, or reboil it. This will cause it to become stringy or separate. Reheat any leftover sauce on low heat, stirring it constantly until it is ready to serve.

Summary:
Gather your ingredients. Melt 4 tablespoons of butter. Whisk in 4 tablespoons of flour. Add 3 cups of milk. Add 1 teaspoon spices. Remove the sauce from the heat. Stir in the shredded cheese. Serve immediately. Store any leftover sauce in an airtight container in the refrigerator.