Preheat oven to 350°. Dust a greased 13×9-in. baking dish 1/4 cup matzo meal; set aside.
In a large bowl, combine apples, 1/4 cup sugar and cinnamon; set aside. In another large bowl, beat eggs until slightly thickened. Gradually add remaining sugar, beating until thick and lemon-colored. Beat in oil and water. Combine potato starch and remaining matzo meal; add to egg mixture and mix well.
Pour half of batter into prepared pan. Top with apples and remaining batter. Bake until a toothpick inserted near the center comes out clean, 40-45 minutes. Cool on a wire rack. If desired, top with whipped cream.