Heat oven to 350º F.
In 9- to 10-inch ovenproof skillet over medium heat, melt butter. Add brown
sugar and stir about 6 to 7 minutes, or until mixture coats the back of a
spoon. Remove and set aside. Drain pineapple thoroughly. Pack snugly over
melted butter-sugar mixture in skillet. Set skillet aside.
Separate eggs, putting the whites into large bowl, yolks into smaller one.
Whisk melted butter and almond extract into egg yolks; set aside. In a separate
bowl, sift together flour, baking powder and salt; set aside.
With electric beater or whisk, beat egg whites just until they form firm peaks.
(Do not overbeat.) Fold granulated sugar into egg whites, about ¼ cup at a
time. Fold in egg yolk mixture, about one-quarter at a time. Finally, fold in
flour mixture, about ¼ cup at a time. Pour batter over pineapple and spread
with spatula to cover.
Bake for 30 minutes, or until toothpick inserted into center comes out clean.
Remove and let stand at least 10 minutes before unmolding. The sides will have
pulled away slightly. To unmold, run knife around edges, then place large plate
or platter over top of skillet. Holding plate and skillet tightly together (be
careful, pan and juices are hot), flip them over so skillet is on top. The cake
will fall onto plate.