A roux in creole cooking is made with two ingredients, flour and oil. A French roux is made with flour and butter. To make a dark brown roux the flour and oil are cooked and stirred together for about 30-45 minutes until it becomes dark brown almost like chocolate and the consistency is close to that of dough. Most people at home don't have the time or the skill to allow the roux to cook that long with burning it, so a medium brown or brown roux is often used. The cooking process is the same but is cut down to 15 minutes.