Buckle up

Blueberry Buckle

Recipe from Cook's Illustrated July & August 2005

INGREDIENTS
Streusel
1/2 cup (2 1/2 ounces) unbleached all-purpose flour
1/2 cup (3 1/2 ounces) packed light brown sugar
2 tablespoons granulated sugar
1/4 teaspoon ground cinnamon
Pinch table salt
4 tablespoons (1/2 stick) unsalted butter, cut into 8 pieces, softened but still cool

Cake
1 1/2 cups (7 1/2 ounces) unbleached all-purpose flour
1 1/2 teaspoons baking powder
10 tablespoons (1 1/4 sticks) unsalted butter, softened but still cool
2/3 cup (about 4 3/4 ounces) granulated sugar
1/2 teaspoon salt
1/2 teaspoon grated zest from 1 lemon
1 1/2 teaspoon vanilla extract
2 large eggs, room temperature
4 cups (about 20 ounces) fresh blueberries, picked over

PREPARATION

1. FOR THE STREUSEL: Mix flour, sugars, cinnamon, and salt until well combined and no large brown sugar lumps remain. Add butter and mix until until mixture resembles wet sand and no large butter pieces remain. Set aside.

2. FOR THE CAKE: Adjust oven rack to lower-middle position; heat oven to 350 degrees. Spray 9" round cake pan with 2" sides with non-stick cooking spray, line bottom with parchment paper round, and spray parchment; dust pan with flour and knock out excess.

3. Whisk flour and baking powder in a small bowl; set aside. In standing mixer fitted with a flat beater, cream butter, sugar, salt, and lemon zest at medium-high speed until light and fluffy, about 3 minutes; using rubber spatula, scrape down bowl. Beat in vanilla until combined, about 30 seconds. With mixer running at medium speed, add eggs one at a time; beat until partially incorporated, then scrape down bowl and continue to beat until fully incorporated (mixture will appear broken). With mixer running on low speed, gradually add flour mixture; beat until flour is almost incorporated, about 20 seconds. Stir batter with rubber spatula, scraping bottom and sides of bowl, until no flour pockets remain and batter is homogenous; batter will be very heavy and thick. Using rubber spatula, gently fold in blueberries until evenly distributed.

4. Transfer batter to prepared pan. Spread batter evenly to pan edges and smooth surface. Squeeze portion of streusel in hand to form large clump; break up clump with fingers and sprinkle streusel evenly over batter. Repeat with remaining streusel. Bake until deep golden brown and toothpick or wooden skewer inserted into center of cake comes out clean, about 55 minutes. Cool on wire rack 15-20 minutes (cake will fall slightly as it cools).

5. Run paring knife around sides of cake to loosen. Place upside-down plate (not serving platter) on top of cake pan; invert cake to remove from pan, lift off cake pan, then peel off and discard parchment. Invert cake onto serving platter. Cool until just warm or to room temperature, at least 1 hour. Cut into wedges and serve.