Preheat oven to 350 degrees. Line a 9x13 baking pan with parchment paper or aluminum foil, leaving enough overhang to use as a sling to remove the blondies from the pan. Spray with non-stick spray and set aside.

Whisk the gluten free flour, baking powder, and salt together in a small bowl. Set aside.

Add the melted butter and brown sugar to a large bowl and whisk to combine. Whisk in the eggs and vanilla extract until the eggs are completely incorporated.

Stir in the dry ingredients and mix until just combined. Fold in the semisweet and white chocolate chips.

Transfer the batter to the prepared pan, spreading it evenly throughout the pan. Bake on the center rack for 22-24 minutes or until just done. Don't overbake!

Cool completely on a wire rack before removing from the pan and cutting into bars.