Make a well in the centre of the dry ingredients and mix in the melted butter.
Press firmly into prepared tray and bake for 25 minutes.
Remove from oven and cool in tray.
To make icing mix icing sugar and cocoa over a bowl of hot water. Add a little hot water to make the icing to a good spreadable consistency. Spread over cooled slice.
Cut into squares.
Notes
My Gluten Free flour is a blend of brown rice flour, corn flour and tapioca flour