To make this Pecan Snow Cookies Recipe gluten free, replace the all-purpose flour with a certified gluten-free 1:1 baking flour blend. Verify that the powdered sugar, vanilla extract, pecans, butter, salt, and all packaged ingredients are labeled gluten free or free from gluten-containing additives. Use clean mixing bowls, utensils, measuring cups, baking sheets, and cooling racks to prevent cross-contact with gluten-containing ingredients.