Preheat the oven to 325°F. Spray a 8in x 8in pan with non-stick vegetable spray (preferably PAM® For Baking or Baker’s Joy), and use a pastry brush to spread it evenly.
Sift the gluten-free flour, xanthan gum and baking soda into a mixing bowl. Add the salt, then whisk well to combine, set aside.
Place the butter(cut into smaller chunks), sugar and water into a microwave safe bowl and microwave for 2 minutes then stir. Continue to microwave at one minute intervals until the butter and sugar have melted. Alternatively you can melt the mixture in a saucepan on the stove.
Add the chocolate chips to the warm butter mixture and let sit for about five minutes. Stir the mixture until all the chocolate chips are melted.
Break the eggs into a separate bowl and whisk slightly, then add them to the melted chocolate mixture. Whisk well to combine.
Add the flour mixture to the chocolate mixture and whisk until just combined, do not over mix.
Pour the batter into the prepared pan and bake at 325°F for 40 minutes. Allow to cool completely before cutting. Store in an airtight container for a few days, refrigerate for longer storage