Preheat oven to 350°F. Spray three 6 inch pans with cooking spray and line bottom with parchment.
Using a spice grinder or something similar, grind up the freeze dried blueberries until a powder like consistency.
In the bowl of your stand mixer fitted with the paddle attachment, mix together flour, sugar, freeze dried blueberry powder, baking powder and salt until combined.
Cut butter into one inch cubes. With the mixer on low speed add the cubes of butter one at a time. Mix until combined and no large chunks remain.
Add the egg whites and continue to mix on low until incorporated.
With the mixer still on low speed slowly pour in the buttermilk.
Add the vegetable oil and vanilla and mix until fully combined.
Coat the blueberries in the 2 tbsp of flour then fold the blueberries in the batter.
Divide the batter evenly between the three prepared pans.
Bake for 30-40 minutes or until a toothpick comes out clean.
Let the cakes cool in the pans for about 10 minutes and then transfer to a wire rack to cool completly.