1 1/2 cups flour
1/2 teaspoon baking powder
1/2 teaspoon fine salt
1/4 teaspoon baking soda
5 tablespoons butter, softened
2/3 cup sugar
1 teaspoon vanilla
1 large egg
1/3 cup buttermilk
3/4 cup blueberries

Lemon Cream Cheese Filling:

4 ounces cream cheese, softened

4 tablespoons unsalted butter, softened

1 1/2 cups powdered sugar, sifted

1/2 teaspoon vanilla extract

Pinch salt

1 teaspoon lemon zest, optional

1 teaspoon lemon juice, optional