To make this recipe gluten-free make sure you use oats that are certified as gluten-free. Oats themselves don't contain gluten. They can sometimes come into contact, with grains that do during processing. So look for oats that are labeled as "gluten-free" to ensure they haven't been exposed to any gluten-containing grains. Also remember to check if other ingredients, like chocolate chips and vanilla extract, are also certified as gluten-free to keep your No Bake Chocolate Oat Bars free of gluten.