In a small saucepan, melt butter over medium heat.
Whisk in the flour, and allow to bubble and cook for 2-3 minutes.
Whisk in the milk, chicken base, basil, thyme, parsley, onion powder, and kosher salt. Continue to heat, whisking frequently. The mixture will thicken as it comes to a low boil after about 5-7 minutes.
Remove from the heat. Use in recipe as directed, or cover and refrigerate for up to 3 days until ready to use.