In a stand mixer, cream butter, then add sugars and beat until light and fluffy. Add eggs and vanilla and mix to combine.
In a separate bowl, combine flour, baking powder and salt; mix well. Combine buttermilk, lemon zest and lemon juice in another small bowl. Add dry ingredients to creamed mixture alternately with buttermilk-lemon mixture. Mix until just combined.
Toss blueberries with 1 tablespoon flour and gently fold into the cake batter. Batter will be very thick; do not overmix.
Spoon batter evenly into prepared cake pans. Bake for approximately 21 to 25 minutes or until a toothpick inserted into the center comes out clean. Remove from the oven and cool completely in the pan before assembling and frosting.