In a medium bowl, whisk together the flour, baking powder and baking soda. Set the dry ingredients aside.
2 1/2 cups (300g) all-purpose flour, 1 Tbsp baking powder, 1/2 tsp baking soda
In a large bowl, whisk together the granulated sugar and the melted butter, until combined.
1 1/4 cup (250g) granulated sugar, ½ cup (113g) salted butter
Add the eggs, one at a time, beating after each one until it is fully incorporated.
3 large eggs
Add the buttermilk and the vanilla to the mixture and beat until the mixture is smooth.
1 ¼ cup (300mL) buttermilk, 1 tsp vanilla
Add the flour mixture to the wet ingredients, reserving about ¼ cup of flour, and mix until the flour is just barely incorporated.
Toss the blueberries and white chocolate chips in the last ¼ cup of flour and fold them into the batter.**
1 cup (6oz) blueberries, 1 cup (6oz) white chocolate chips
Cover the bowl and allow the batter to rest for half an hour.