Cream first 2 ingredients together.
Sift flour, baking powder and salt together, and add alternately with milk.
Spread into a well-buttered 9x12-inch pan.
Blend the last 4 ingredients, and sprinkle on top.
Bake at 375 degrees 25 to 30 minutes.
Frozen berries may be used, but be sure to rinse and pat dry before blending them into the batter...or the juice will turn the batter blue.