Blueberry Breakfast Cake with a hint of lemon

I found this recipe here. I made a few mistakes and changes from their recipe but it came out perfect for us!

½ cup unsalted butter, room temperature
zest from 1 large lemon
3/4 c
1 egg
1 tsp. vanilla
2 cups flour
2 tsp. baking powder
1 tsp. kosher salt
2 cups fresh blueberries
1 cup buttermilk (I juiced the lemon first and then filled it to the cup mark.

Preheat the oven to 350ºF. Cream butter with lemon zest and sugar until light and fluffy.

Add the egg and vanilla and beat until combined. Then whisk together the remaining flour, baking powder and salt.

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

Place in greased 9x9 pan and bake for 45 minutes.