Food Network shares how to make a roux, which is the base to thicken sauces and soups. It’s made from equal parts butter or oil and flour. For a light roux, melt butter over medium-low heat, add flour and stir constantly with a wooden spoon in a figure eight for even cooking. In three to five minutes the light roux will be slightly puffed. It can be used in white sauces like white pepper gravy or bechamel sauce. A brown roux is perfect for gravy and will need to cook for six to seven minutes. Dark roux is great for Cajun and Creole recipes and needs to cook for eight to 15 minutes. Keep in mind that the longer a roux cooks, the less thickening power it will have. Always let your roux cool slightly before adding another liquid, like stock or milk, then whisk and simmer to your desired thickness.