In a medium bowl, toss the blueberries with a small amount of the measured flour. Set aside. You don't need extra flour for this...just use a tablespoon or two of the two cups needed.
In a large bowl, cream together the butter and sugar.
Add the egg and vanilla and beat until combined.
Add the buttermilk and stir well.
Add the remaining flour, baking powder and salt. Stir just until combined.
Fold in the floured blueberries.
Spread batter evenly in the prepared pan.
Bake for 40 to 45 minutes until a toothpick comes out clean.
Let cool for 15 minutes before serving.
The calories shown are based on the cake being cut into 15 pieces, with 1 serving being 1 slice of cake. Since different brands of ingredients have different nutritional information, the calories shown are just an estimate. **We are not dietitians and recommend you seek a nutritionist for exact nutritional information.**