Step 1

Preheat the oven to 375°F. Lightly grease an 8" square, 9" square, or 9" round cake pan; make sure your pan of choice is at least 2" deep.

Step 2

, To make the streusel topping: Mix the sugar, flour, cinnamon, and salt in a small bowl. Work in the butter until the mixture becomes evenly crumbly. Set aside.

Step 3

, To make the cake: In a medium-sized mixing bowl, whisk together the flour, baking powder, and salt.

Step 4

, In a separate bowl, beat together the sugar, butter, egg, and vanilla.

Step 5

, Add the flour mixture and the milk alternately to the sugar/butter mixture, beginning and ending with flour. Gently stir in the blueberries.

Step 6

, Pour the batter into the prepared pan. Sprinkle the streusel on top.

Step 7

, Bake the cake for 45 to 50 minutes, or until a toothpick or knife inserted into the center comes out clean.

Step 8

, Remove the cake from the oven, and set it on a rack to cool for 10 minutes. Serve right from the pan. Or to transfer to a serving plate, loosen the sides with a knife or spatula. Holding the pan in one hand, gently tip the cake out onto your other hand, remove the pan, and turn the cake topping-side up onto a serving dish.

Step 9

, Store cake, covered, for a couple of days at room temperature; wrap securely and freeze for longer storage.