1. Preheat the oven to 350ºF. Cream butter with lemon zest and 3/4 cup of the sugar until light and fluffy.

2. Add the egg and vanilla and beat until combined. Meanwhile, toss the blueberries with ¼ cup of flour, then whisk together the remaining flour, baking powder and salt.

3. Add the flour mixture to the batter a little at a time, alternating with the buttermilk. Fold in the blueberries.

4. Grease a 9x13-inch baking pan with butter or coat with non-stick spray. Spread batter into pan. (The batter will be very thick) Sprinkle batter with 2 tablespoons of sugar.

Bake for 35 minutes. Check with a toothpick for doneness. If necessary, return pan to oven for a couple of more minutes. (Note: Baking for as long as 10 minutes more might be necessary.) Let cool at least 15 minutes before serving.