In a 10 inch heavy skillet with a heat-resistant handle (I use a cast iron skillet), melt 1/2 cup butter or margarine over very low heat. Remove from heat, and sprinkle brown sugar evenly over pan. Arrange pineapple slices to cover bottom of skillet. Distribute cherries around pineapple; set aside.
Sift together flour, baking powder, and salt.
Separate the eggs into two bowls. In a large bowl, beat egg whites just until soft peaks form. Add granulated sugar gradually, beating well after each addition. Beat until stiff peaks form. In a small bowl, beat egg yolks at high speed until very thick and yellow. With a wire whisk or rubber scraper, using an over-and-under motion, gently fold egg yolks and flour mixture into whites until blended. Fold in 1 tablespoon melted butter or margarine and almond extract. Spread batter evenly over pineapple in skillet.
Bake for 30 to 35 minutes, or until surface springs back when gently pressed with fingertip. Loosen the edges of the cake with table knife. Cool the cake for 5 minutes before inverting onto serving plate.