Preheat the oven to 325 degrees. Spray a 9 x 13 pan with cooking spray and set aside.

In a medium bowl combine the all purpose flour, brown rice flour, baking powder, baking soda, and salt. Mix and set aside.

In a large bowl combine the brown sugar, sugar, and melted coconut oil. Mix until well combined. Add the egg and mix well.

Add half of the flour mixture to the sugar mixture and mix well. Add in the milk and vanilla and stir until combined. Add the remaining flour mixture and mix until combined.

Fold in the chocolate chips and then dump the mixture into the prepared pan. Press the dough into the bottom of the pan.

Bake for 25-27 minutes or until the edges are golden brown. Remove from the oven and cool completely.

Cut into 20 squares and enjoy!