brown sugar, firmly packed
butter or margarine
confectioners' sugar, sifted
Combine the flour and brown sugar.
Cut in the butter until the mixture resembles coarse meal.
Press 1 1/3 cups of the mixture into an ungreased 8-inch pan.
Combine the remaining crumb mixture, sour cream, egg, baking soda, salt, cinnamon, and vanilla extract, and blend well.
Stir in the blackberries, and spoon over the crust.
Bake at 350F for 35 minutes.
Sprinkle with confectioners' sugar.