Warm the milk in a saucepan or microwave in measuring cup for 1 minute on high.
In a medium sauce pan melt equal parts butter and then add the flour.
Whisk the flour and butter together and allow to simmer on low to cook the flour 1-2 minutes. The lightest (white color) roux will be slightly puffed.
Gradually add the warm milk and whisk to incorporate until a smooth sauce forms on low heat. Cook several minutes, sauce will thicken.
Add a little more milk if too thick and stir in the dry mustard, cheese and Tabasco (several dashes or more to your liking). Whisking until smooth sauce forms.
Store in an airtight container and refrigerate up to four days.
Video
Notes
You can substitute any cheese you prefer to suit your needs.
Store in an airtight container and refrigerate up to four days.