Preheat the oven to 450°F. Spray an 8×8-inch baking pan with cooking spray.
In a medium bowl, whisk together the gluten-free flour, baking powder, sugar, baking soda and salt.
Pour in the buttermilk and stir until a sticky batter forms.
Scoop the biscuit dough into the prepared pan. Using wet hands, spread the dough into an even layer.
Pour the melted butter over top of the biscuits. Using a sharp knife, cut the dough into 9 even squares.
Bake for 25-30 minutes, until golden brown. Let the biscuits cool for 10 minutes before serving.
