Mix together butter, 2 cups sugar, 4 eggs, baking powder, salt, vanilla and milk. Add flour and mix well. Fold in the floured blueberries. Line a 9" x 13" pan with aluminum foil. Pour the batter into the pan and sprinkle the top with mixture of 2tb sugar and 1 ts cinnamon. Preheat oven to 350. Bake for 45 minutes. Remove from pan. Allow to cool before removing aluminum foil.
Note: coating the blueberries with flour stops them from sinking in the batter. The aluminum foil prevents the cake from pulling apart if any of the berries stick, this proves out to be better than greasing the pan. Good luck, grandma rose.