Make your own gluten-free flour. see also Arrowroot powder is another ingredient that can be used in place of xanthan gum, if you are having a hard time finding the latter. As a general rule, use one-half teaspoon of arrowroot powder for each cup of wheat flour called for in any recipe. Note: Round up if the recipe calls for a partial cup. Use 2 1/2 teaspoons baking powder for every cup of flour used in a recipe.