To make these Hershey Syrup Brownies gluten free, replace the flour with a certified gluten-free 1:1 baking flour blend that contains xanthan gum. Also check that the Hershey’s syrup, cocoa powder, vanilla extract, powdered sugar, and baking spray are certified gluten free if needed for strict dietary requirements. Because gluten-free flour blends can vary slightly, begin checking the brownies near the lower end of the baking time to avoid overbaking.