Wash hands. 1] Melt the butter in a sauce pot over medium heat. Add flour all at once, whisking vigorously. When mixture thins and starts to bubble, reduce heat. 2] Cook 4-5 minutes until you smell a toasty aroma. Stir frequently. 3] After the roux has cooled, transfer to a storage container. Cover, label, date, and refrigerate until needed. CCP: Refrigerate at 5°C, or below.