To make this Eggnog Texas Sheet Cake Recipe gluten free, replace the all-purpose flour with a certified gluten-free 1:1 baking flour blend. Verify that the eggnog, powdered sugar, baking soda, vanilla extract, nutmeg, salt, and all packaged ingredients are labeled gluten free or free from gluten-containing additives. Use clean mixing bowls, saucepans, utensils, measuring cups, and a clean baking sheet to prevent cross-contact with gluten-containing ingredients.