Preheat oven to 190° C (375° F).
Peel the apples.
Thinly slice apples and place criss-crossed in a 20 cm (8 in) round or square baking pan. Set aside.
In a saucepan, boil the maple syrup with 60 ml (¼ cup) butter for 5 minutes. Pour over the apples.
In a bowl, whip the other 60 ml (¼ cup) of the butter with the maple sugar. Whisk in the egg. Add the milk, vanilla, flour, baking powder, and salt. Mix well.
Cover the apples with this dough.
Bake 30 to 40 minutes.
Allow to cool 5 minutes and turn out onto a plate.
