In a small sauce pan, melt the butter over medium heat.

Whisk in half & half and heat for several minutes. Keep an eye on the heat so that the sauce doesn't boil.

When the sauce is hot, add the cheese by handfuls, whisking in.

Allow the cheese to melt and turn down the heat to keep sauce hot, but not boiling.

Add flour by a tablespoon at a time until sauce is as thick as you'd like. The sauce will thicken more as it cools.