Separate the yolk and white of the eggs into separate bowls. Divide the sugar evenly among the eggs. Beat the egg yolk and sugar until fluffy. Beat the mixture in the other bowl until the sugar dissolves. Put the milk and oil in the bowl with the egg yolk and beat. Add the flour, cocoa, vanilla, and baking powder to the mirror bowl. Beat with the mixer until they are homogeneous. Then add the Nutella and mix. Add the egg white with the help of a spatula and mix slowly. Put the mortar that you have prepared in a greased tart mold and bake in a preheated oven at 170 degrees. Once baked, add a strip of strips on top of the chocolate sauce. Enjoy your meal ????????