Melt ½ c. butter in 9x13” metal cake pan and brush sides. Add 1 c. brown sugar and spread evenly on bottom. Slice about 4 apples into ½” thick slices across the core perpendicular to the stem. Remove the seed cavity with a paring knife. Place apple slices on top of the brown sugar and cook atop stovetop at medium heat until they are slightly caramelized. Remove from heat. Sift 1 ½ c. flour (I use 50-50 whole wheat) with 1 ½ tsp. baking powder, ¼ tsp salt. Separate 3 eggs. Stiffly beat whites. Beat yolks and add 1 c. sugar beating well and then add ½ c. cider and beat until fluffy; add flour mixture. Then fold in egg whites and pour batter over apples. Bake @ 375 deg. 30 min. Allow to cool very slightly and then turn upside down on a cake plate or cookie sheet.