Grease 3 cast-iron skillets. Drain pineapple rings, reserving juice. Add all but 1 tablespoon of the juice to the buttermilk to make 1.5 cups fluid (equal parts, if possible). Separate eggs; place all the whites in a large bowl, place 3 yolks in one small container, and the other 3 in another. Prepare 3 8-inch cake pans with brown-paper rounds (for bottoms) greased with shortening. Preheat oven to 180ºC . Soften half C butter in a large bowl; add confectioner's sugar and beat until thoroughly mixed. Add 3 egg yolks, one after another, and continue beating. Add vanilla and mix till thoroughly blended, scraping sides with spatula if necessary. Measure flour into a small bowl and stir in baking soda. Add to butter/sugar mixture alternately with buttermilk in 4 steps, beginning and ending with the flour. Sprinkle about half t salt on egg whites. Beat till stiff, but not dry. Fold egg whites into batter. TOPPING: Melt butter in large skillet over medium heat; add 1 T of pineapple juice and the sugar. Add water and Karo and cook at a high, rolling boil for about 3 minutes. Pour equally into prepared cast-iron skillets (about half to 2 cm thick). Place pineapple rings in bottom of each skillet, and in the centers, place a cherry. (Can add pecan halves, too.) Divide batter between pans and bake at 180ºC . about 30-35 minutes, until done.