To make "BGE roux," place the desired amount of flour in a heavy duty cast iron pot and bake at 350 degrees for 30 to 45 minutes, stirring every 15 minutes. You may have to cook it longer to get the desired color. The closer you get to the end of cooking time the more often you need to stir.
Browning the flour gives you the depth of flavor that you achieve in the classic dark roux, with a much simpler method. You can prepare the BGE-baked roux while you chop the vegetables for a gumbo, stew or etouffee. BGE roux as most rouxs can be made and stored in a jar for future use.