2 1/2 cups all-purpose flour
2 teaspoons baking powder
1/2 teaspoon baking soda
1/2 teaspoon salt
2/3 cup granulated sugar
1 1/3 cups blueberries, picked over
2 large eggs, lightly beaten
2 teaspoons vanilla extract
1 cup plus 2 tablespoons buttermilk
9 tablespoons (1 stick plus 1 tablespoon) unsalted butter, melted and cooled to tepid
Preheat the oven to 375 degrees F. Film the inside of an 8 by 8 by 2-inch baking pan with nonstick flour-and-oil spray.
For the batter, sift the flour, baking powder, baking soda, salt, and sugar into a large mixing bowl. Whisk the mixture thoroughly. In a small mixing bowl, toss the blueberries with 2 1/2 teaspoons of the sifted flour mixture.
Place the eggs and vanilla extract in a medium-size mixing bowl and whisk well. Blend in the buttermilk and melted butter. Pour the buttermilk mixture over the flour mixture, scatter over the blueberries, and stir to form a batter, using a flexible rubber spatula. The batter will be dense.
Scrape the batter into the prepared baking pan, smoothing it into an even layer, using a rubber spatula or narrow offset palette knife.
Bake the cake in the preheated oven for 40 minutes, or until risen, set, and golden brown on top. A wooden pick inserted 1 inch from the center will withdraw clean.
Cool the cake in the pan on a cooling rack for 10 minutes. Invert the cake onto another cooling rack, lift off the baking pan, then invert again to stand right-side up. Cool completely. Cut the cake into squares for serving, using a serrated knife. Store in an airtight cake keeper.
one eight-inch cake, sixteen squares
on baking day, or up to 1 day in advance, stored in an enclosed container
◊ use the thickest buttermilk available, and whisk it well before measuring
◊ if you like, either 1/4 teaspoon freshly grated nutmeg or 1/2 teaspoon ground cinnamon may be sifted into the dry ingredients