Black and Blue Berry Breakfast Cake

Heather made this for us in early July and it was delicious.  A few days ago, Elliott and Ann Nielson gave us some of their blackberries so we thought, "Black AND Blue Berry Cake. . . "  So we added 50% more to the ingredients in the original recipe and cooked it in a 9"x12" pan.

3/4 cup unsalted butter, room temperature
3 tsp. lemon zest or more — zest from 1 large lemon
1 1/2 c + 1 tablespoon sugar**
1 1/2 egg, room temperature (scramble two eggs together: take out a tablespoon of egg [cook it in the microwave for a snack while you finish the cake])
1 1/2 tsp. vanilla
3 cups flour
1 TB baking powder
1 1/2 tsp. kosher salt
2 cups fresh blackberries

1 cup fresh blueberries

3/4 cup buttermilk

** This 1 tablespoon is for sprinkling on top

1. Preheat the oven to 350ºF.  Zest the lemon (put parchment paper over the grater before rubbing the lemon on it, then when you lift off the paper, all the zest comes with it.  No more scraping the grater with a toothpick) Cream butter with lemon zest and 1 1/2 cup of the sugar until light and fluffy.

2. Add the eggs and vanilla and beat until combined. Meanwhile, toss the berries 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 berries.

4. Grease a 9"x12"-inch baking pan (or something similar) with butter or coat with non-stick spray. Spread batter into pan. Sprinkle batter with remaining tablespoon 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.