He used double-strength vanilla and was generous with the cinnamon. The brown sugar was a very dark one which seemed less sweet than the typical supermarket brown sugar.

Blueberry Coffee Cake V3.0

(makes one 9-by-9-inch cake, creating 16 squares)

Nonstick cooking spray, for preparing baking pan

For cinnamon and sugar topping:

1/6 cup granulated sugar

1/6 cup firmly packed light brown sugar, sieved if lumpy

2 teaspoons ground cinnamon

For cake batter:

1 cup thick, cultured sour cream

1/2 teaspoon baking soda

1 1/2 cups plus 2 tablespoons unsifted bleached all-purpose flour

1/4 cup unsifted bleached cake flour

3/4 teaspoon baking powder

1/4 teaspoon salt

1/2 teaspoon ground cinnamon

1/2 teaspoon freshly grated nutmeg

2 cup fresh blueberries

1/2 cup dried blueberries

1 stick unsalted butter, softened

1 cup superfine sugar

2 large eggs

2 teaspoons pure vanilla extract

Preheat oven to 350 degrees. Film the inside of a 9-by-9-by-2-inch baking pan with nonstick cooking spray; set aside.

In a small mixing bowl, thoroughly combine granulated sugar, light brown sugar, and cinnamon; set aside.

Combine sour cream and baking soda in a medium-size mixing bowl. The mixture will swell and puff a bit as it stands.

Sift flours, baking powder, salt, cinnamon, and nutmeg onto a sheet of waxed paper. In a small mixing bowl, thoroughly toss blueberries with 1 1/2 teaspoons of sifted mixture. The blueberries must be well coated with the flour mixture, so that they remain suspended in the cake batter.

Cream butter in large bowl of a freestanding electric mixer on moderately low speed for 2 minutes. Add superfine sugar and beat 1 to 2 minutes. Beat in eggs, one at a time, blending well after each addition. Mix in vanilla extract.

On low speed, add half of sifted ingredients, the sour cream-baking soda blend, then the remaining sifted mixture. Scrape down the sides of the mixing bowl frequently with a rubber spatula to keep the batter even-textured. The batter will be moderately thick. Fold in blueberries.

Scrape batter into prepared baking pan. Smooth over the top with a rubber spatula or flexible palette knife. Sprinkle topping evenly over surface of batter.

Bake cake in preheated oven for 45 – 50 minutes, or until set and a wooden pick inserted in the cake withdraws clean. Cool cake in pan on a rack for at least 20 minutes before cutting into squares for serving. Serve cake warm or at room temperature.