Melt butter in a dutch oven. Remove from heat. Stir in flour until it's combined. Put back on the stove and heat, continuing to stir for a few minutes.
Slowly whisk in the chicken broth. I usually use a wooden spoon or a large plastic (not picnic) spoon. Bring to a boil, then turn down to a simmer. It will begin to thicken a bit.From this roux, you can make different soups.