Peel the apples, remove the core and cut into wedges. Rub the lemon peel and squeeze the lemon. Drizzle the prepared apples with the lemon juice.
Beat the margarine, 125 g sugar, salt, lemon zest and eggs until frothy. Mix the flour, cornstarch and baking powder and stir into the egg mixture, tablespoon at a time. Pour the batter into a springform pan and distribute the apple wedges evenly over it. Bake at 175 degrees (hot air) for 30 minutes.
In the meantime, bring the remaining ingredients to the boil and let them brown lightly. At the end of the 30 minutes, take the cake out of the oven and distribute the caramel mixture evenly over it. Bake for another 20 minutes at 175 degrees. Let cool and carefully remove from the mold.