Place butter, icing sugar, eggs and almond flour in a planetary mixer and mix. Add the flour in two steps and leave to rest in the fridge for at least 8 hours.
Peel two apples and squeeze some lemon, add a spoonful of cinnamon and one of brown sugar. Leave to rest in the fridge for 30 minutes.
Form the tarts and bake at 170°C for about 25 minutes. When they have cooled, add the apricot jam, then the pieces of panettone and finally the apples.