To make this recipe gluten-free, ensure that the confectioners’ sugar and semi-sweet chocolate are certified gluten-free, as some brands may include additives or be produced in facilities that process wheat. Additionally, double-check that the shortening and vanilla extract are gluten-free. The core ingredients—peanut butter, butter, and chocolate—are typically gluten-free, but label verification is essential for individuals with gluten sensitivity or celiac disease.