Determine the sauce thickness needed and thicken by adding more flour. A thinner sauce is good for casseroles and gravies; a thicker sauce is better for enchiladas and curry dishes.
In a medium saucepan over medium heat, melt the butter.
Add flour and whisk until well combined, about 1 minute. Working quickly (the flour and butter will burn if not attended), whisk in the chicken broth.
Continue whisking until the mixture just begins to bubble and thicken. If sauce needs thinning, whisk in 1-2 tablespoons of milk or more chicken broth.
Once cooked to desired consistency, reduce heat to a simmer and add seasonings to taste.
Remove from heat and use in desired recipe.