In a large bowl, mix sugar, lemon zest, and orange zest. Using your fingers, mix these two ingredients well to achieve a beautiful colour of the cake.
6 Pour in the milk, oil, vanilla, and mix until the sugar dissolves.
7 Sift the flour and baking powder, then incorporate them with a whisk into the liquid mixture. Try not to overmix as the cake won't be as fluffy.
8 Pour the batter over the caramelized apples and place the dish in the preheated oven at 180 degrees Celsius for 30 minutes or until it passes the toothpick test.
9 Remove the cake from the oven, place a plate on top, and carefully flip it.
Enjoy your meal!