Thoroughly cream shortening and ½ cup sugar; add egg and mix well. Sift 2 cups flour, baking powder, and salt. Add to creamed mixture alternately with milk. Pour into well-greased 11 ½ x 7 ½ x 1 ½ inch pan. Sprinkle blueberries over batter.
Combine ½ cup sugar, ½ cup flour, cinnamon, and butter till crumbly; sprinkle over blue berries. Bake in moderate oven (350 degrees) 45 to 50 minutes. Cut in squares. Serve warm.