Melt the butter over low heat and then add the cornstarch, stirring until well combined. (You can use a fondue pot or a saucepan on the stove - either method works great! If you have an electric fondue pot, turn the temperature slightly above warm as the temperature gets very hot if you go higher than this!)

Mix the salt in well and then add the milk. Stir continually over medium-low heat until boiling. Continue to stir and boil the mixture for one minute.

Turn the heat down slightly and then add the cheese. Mix just until the cheese is melted and then serve with all of your favorite dippers!