Blueberry-Cinnamon Coffee Cake

Steps

1. 1

   Heat the oven to 350°F (180 °C) (175°C (350 °F)) and set a rack in the center. Spray an 8-by-8-inch square pan with nonstick cooking spray, then line it with a strip of parchment paper that overhangs two sides.

2. 2

   Make the crumb topping. In a medium bowl, combine the flour, light brown sugar, rolled oats, cinnamon, and salt. Add the softened butter and work it together with your fingertips until evenly moistened and pebble-size crumbs form.

3. 3

   Make the cinnamon swirl. In a small bowl, combine the granulated sugar and cinnamon, then set the mixture aside.

4. 4

   Make the cake batter. In a large bowl, beat the sugar and softened butter with an electric mixer on medium-high speed until light and fluffy, about 4 minutes.

   Start 4-minute timer
5. 5

   Add the eggs one at a time, mixing each egg in completely before adding the next. Add the sour cream, cinnamon, vanilla, and salt, and beat until combined.

6. 6

   Stop the mixer and add the cake flour, baking powder, and baking soda. Mix on low speed just until combined.

7. 7

   Toss the blueberries with the remaining 1 tablespoon flour. Gently fold the floured blueberries into the batter.

8. 8

   Spoon half of the batter into the prepared pan and smooth it into an even layer covering the bottom.

9. 9

   Sprinkle the cinnamon-sugar mixture evenly over the batter.

10. 10

    Spoon the remaining batter over the cinnamon sugar and gently smooth it into an even layer.

11. 11

    Sprinkle the crumb topping evenly over the cake batter.

12. 12

    Bake for 45 to 55 minutes, until the cake is puffed and golden and a tester inserted into the center comes out clean.

    Start 55-minute timer
13. 13

    Serve warm or at room temperature. Store the cake loosely wrapped at room temperature for up to 3 days.