Step 2
In a dutch oven or medium pot, set over medium heat, add the butter. When melted, add the celery, carrot and thyme. Cook until slightly softened, about 2 to 3 minutes. Mix in the flour and cook for about 1 minute. Next pour in the chicken stock. Bring the mixture to a simmer and then immediately bring it down to medium low; cook for about 6 to 7 minutes, until slightly thickened.