In a small bowl, whisk together the flour, baking powder, and salt.
Use an electric mixer or a stand mixer to cream together the butter and sugar until light and fluffy. Add in blueberries and cream at a high speed. You want to "mash" the blueberries into the mixture, making it so that they are puréed and fully combined with the butter and sugar. The mixture should be a deep purple color.
Gradually fold the dry ingredients into the wet ingredients to form a cohesive dough. Mix in the white chocolate chips. The dough will be pretty wet, so chill in the freezer for 30 minutes to firm it up before baking.
Shape the dough into 12 equal sized balls. Bake the cookies at 400° F for 10-12 minutes or until slightly brown on the edges. Let cool on a cooling rack for 5-10 minutes and then serve.