Blueberry Streusel Cake

By OralW

Ingredients

• For cake:
• For streusel topping: 1 cup all-purpose flour
• 1 tablespoon plus 1 teaspoon packed dark brown sugar 1 tablespoon plus 1 teaspoon granulated sugar
• 3/4 teaspoon cinnamon
• 1/2 stick cold unsalted butter, cut into 1/2-inch pieces
• 1 cup all-purpose flour
• 1 teaspoon baking powder 1/4 teaspoon baking soda 1/2 teaspoon salt
• 1/2 cup sour cream
• 3/4 teaspoon pure vanilla extract 1/2 stick unsalted butter, softened 3/4 cup granulated sugar
• 1 large egg
• 1/2 pound blueberries (31/4 cups)
• Accompaniment: sweetened whipped cream

Details

Servings 16

Preparation

Step 1

Preheat oven to 350°F with rack in middle. Line bottom and sides of a 9-inch square baking pan with heavy-duty foil, leaving an overhang on 2 sides. Butter bottom and sides of pan, then dust with flour, knocking out excess.
Make streusel topping:
Stir together flour, sugars, cinnamon, and a pinch of salt in a large bowl. Blend in butter with your fingertips or a pastry blender until mixture forms large clumps.
Make cake:
Whisk together flour, baking powder, baking soda, and salt in a bowl.
Stir together sour cream and vanilla in a small bowl.
Beat together butter and sugar in a large bowl with an electric mixer at medium-high speed until pale and fluffy, about 5 minutes. Add egg and beat until well blended.
At low speed, mix in flour mixture in 3 batches, alternating with sour-cream mixture and mixing until just