To make this Cheesy Garlic Butter Steak Toast gluten free, use certified gluten-free garlic toast or gluten-free bread prepared with gluten-free garlic butter and cheese. Confirm that the shaved cheesesteak meat, mozzarella, provolone, butter, olive oil, salt, and black pepper are gluten free. Use clean cookware, utensils, and a separate prep surface to avoid cross-contact with gluten-containing ingredients.