In a 10-inch heavy skillet with a heat-resistant handle (I use a cast iron skillet), melt 1/2 cup butter 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 medium-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 until surface springs back when gently pressed with fingertip and a toothpick inserted in the center comes out clean, about 30 to 35 minutes. Loosen the edges of the cake with table knife. Cool the cake for 5 minutes before inverting onto serving plate.