Spray a 9” x 5” baking pan with cooking spray. Set aside.

In the bowl of a stand mixer, add the butter and coconut sugar and beat on medium speed for 30 seconds until light and fluffy.

Add in the egg and vanilla extract and beat on high for 1 minute until combined.

In a medium bowl, combine the flour mix, baking powder, arrowroot flour, salt and xanthan gum.

With the stand mixer turned on, add in the flour to the butter mixture, alternatively with the buttermilk. Add 2 large spoonfuls of flour mixture, then a dash of buttermilk. Repeat until all liquid and dry ingredients are gone and fully mixed.

Let mixture sit for 5 minutes. While the batter is resting, preheat the oven to 350 F.

Meanwhile, toss the blueberries with a dash of the flour mix. Gently fold the blueberries in to the batter.

Spread the batter into the pan and bake for 50 minutes.

Cool in the pan for 5 minutes before removing to a wire rack to cool completely.