Old-fashioned Blueberry Buckle Coffee Cake

I first had this delightful single-layer coffee cake in Macon, GA, from the equally delightful Myrl T. Since it is apparently not in my nature to follow a recipe exactly, I've tinkered with this one just slightly. Now I don't remember which parts of the recipe are original and which have been added by me. Either way, this is how I make it. I can't wait for the summer's fresh blueberries, so we can have a few buckles around our house.

Blueberry Buckle
For the Buckle:
2 c. plus 2 T. all purpose flour, separated and sifted
2 t. baking powder
1/2 t. salt
1/4 c. (1/2 stick) butter, softened
3/4 c. sugar
1 egg
1/2 c. buttermilk milk
1 pint blueberries
1 t. lemon juice

For crumb topping:
1/4 c. butter, softened
1/2 c. sugar
1/3 c. all purpose flour, sifted
1/2 t. cinnamon

Whipped cream, optional (try one of my Flavored Whipped Cream ideas at left)

Preheat the oven to 375. Grease an 8-inch spring-form, square, or round pan. Sift together 2 cups of flour, baking powder and salt. Reserve. Cream the butter and sugar. Beat in the egg. Add the flour mixture, alternating with the buttermilk. Toss blueberries with the lemon juice. Drain any excess liquid and then toss with 2 tablespoons of flour. Fold berries into the batter. Pour batter into the prepared pan. Combine ingredients for topping with a fork to make a mixture that resembles coarse crumbs. Sprinkle topping over the batter. Bake for about an hour until cake tester comes out clean. Serve with whipped cream.