Preheat oven to 375 degrees F. Butter and flour a 9 by 13-inch baking pan.
Cream the sugar and the butter in a mixer. Add the egg and mix well. Sift the dry ingredients and add them to the butter/sugar mixture, alternating with the milk. Fold in the blueberries and pour the batter into the pan.
Topping: Combine all of the ingredients using a pastry blender or in an electric mixer with the paddle attachment. Sprinkle over the batter and bake for 35 to 45 minutes.