Crack the egg and separate egg yolk and white.
Whisk white egg, incorporate sugar and keep on whisking into a still, frothy and smooth peak.
Whisk egg yolk and milk in a different bowl, add oil, flour and sieved baking powder, one pinch of salt and some untreated grated lemon rind.
Whisk the mixture into a uniform peak.
Add and incorporate whisked white egg with a spatula.
Butter and flour 8 holes of a cupcake tray and place 8 parchment disks on the bottom of each hole.
Pour the mixture up to the third part of the holes, carefully avoiding overflow during the cooking.
Pour a spoonful of jam on the surface of each cupcake. While cooking, jam will settle on the bottom, resulting in an upside down effect.
Bake in pre-heated oven at 170 °C for approximately 22 minutes.
Use a stick to test cooking before taking out of the oven.
Once cooked, leave cupcakes cool down before removing them from the tray.
If you like, finish with icing sugar before serving.