Originally Posted by After Shock Media

Ok start with your mother sauce (Bechamel in this case)

Bechamel sauce:
2 tablespoons butter.
2 tablespoons flour.
Quarter teaspoon salt.
Cup of milk.

Melt the butter, whisk in the flour and salt. Stir and cook it over med-low heat for about a minute. Whisk in the milk, keep stirring over med-low heat until thickened.

Cheese sauce:
Add in 1 cup shredded cheese when bechamel is thickened. Stir into sauce until melted. You can add in a little more cheese if you want it extra cheesy and thick.

Above cheese sauce works well to make mac n cheese though I add some dry mustard. To go the nacho route I stir in some minced serranos and a dash of cayenne pepper. You can switch or blend cheeses as well, like try some pepper jack with the cheddar or alone for nachos.