Heat oven to 350 degrees F.
While oven is heating, place butter in 9-inch round baking pan. Place in oven to melt, about 1 minute. Using oven mitt, remove pan from oven. Sprinkle brown sugar evenly over melted butter. Arrange pineapple slices over butter mixture, overlapping slightly. Place cherry halves, cut side up, in center of pineapple slices.
Stir together the flour, baking powder and salt in a medium-size bowl until well blended.
Beat together the granulated sugar, eggs and egg whites in large bowl on medium speed 3 minutes. Mix in the vanilla.
Alternately beat flour mixture and sour cream into egg mixture. Continue beating 2 minutes. Spread evenly over pineapple in pan.
Bake in 350 degree F oven about 30 to 35 minutes or until cakes springs back when lightly touched with fingertip. Cover loosely with foil if browning too quickly. Cool in pan on rack 10 minutes. Invert onto plate. Makes 10 servings.