Preheat your oven to 400F.
In a small bowl, whisk together the flour, baking powder and salt.
Either in the microwave or on the stovetop, thaw the frozen blueberries until they are soft and jammy. In the microwave this should take about 30 seconds on high heat, and on the stovetop it should take about 2-3 minutes on medium heat.
Let the blueberries cool for about 2-3 minutes. While they are cooling, use an electric mixer or a stand mixer to cream together the butter and sugar. You want to cream the sugar and butter until the mixture is noticeably lighter and fluffy.
Add the blueberries to the butter and sugar and cream at a high speed. You want to essentially “mash” the blueberries into the mixture, making it so that they are pureéd and fully combined with the butter and sugar. The mixture should be a deep purple color.
Gradually fold the dry ingredients in with the wet ingredients to form a dough. Mix in the white chocolate chips.
The dough will be very slack, so chill in the freezer for 30 minutes before shaping into 12 balls.
Bake the cookies at 400F for 10-13 minutes or until slightly brown on the edges. Let cool on a cooling rack for 5-10 minutes and then serve!