Classic Blueberry Crumb Cake
Source: Martha Stewart
Makes 1 nine-inch cake

2 1/2 cups all-purpose flour
1 teaspoon baking soda
1 teaspoon baking powder
1/4 teaspoon coarse salt
10 tablespoons (1 1/4 sticks) unsalted butter, room temperature, plus more for pan
1 cup granulated sugar
3 large eggs
1 teaspoon pure vanilla extract
1 1/4 cups sour cream
3 cups blueberries
Crumb Topping (recipe follows)
Confectioners’ sugar, for dusting

Preheat oven to 350F. Butter a 9-inch square baking pan; set aside.

Sift together flour, baking soda, baking powder, and salt into a bowl; set aside.

In the bowl of electric mixer fitted with the paddle attachment, cream butter and granulated sugar until light and fluffy, about 4 minutes.

Add eggs, one at a time, until well combined. Add vanilla, and beat until combined. Add reserved flour mixture and the sour cream, and beat just until well combined. Fold in 2 cups blueberries. Spoon batter into prepared pan.

Toss remaining cup blueberries with the crumb topping. Sprinkle crumb topping over cake.

Bake until golden brown and cake tester comes out clean, 50 to 60 minutes. Dust with confectioners’ sugar before serving.

CRUMB TOPPING
Makes enough for 1 nine-inch cake

1 1/2 teaspoons ground cinnamon
1/2 teaspoon coarse salt
1/2 cup packed light-brown sugar
1 1/2 cups all-purpose flour
12 tablespoons (1 1/2 sticks) unsalted butter, room temperature

In a medium bowl, combine cinnamon, salt, sugar, and flour. Cut in the butter using your hands, two knives, or a pastry blender until well combined and crumbly.