To make this Baked Protein Bar Recipe gluten free, use certified gluten-free protein powder, gluten-free coconut flour, and a gluten-free granulated sweetener. Verify that the peanut butter and cocoa powder are labeled gluten free or free from gluten-containing additives. Use clean bowls, utensils, parchment paper, and baking dishes to prevent cross-contact with gluten-containing foods.