Separate the egg. Cut butter into pieces. Sieve 100 g icing sugar into a bowl. Add flour, butter, vanillin sugar and 2 egg yolks. Knead first with the dough hooks of the hand mixer, then with your hands to a smooth dough. Wrap the dough in foil and chill for about 30 minutes
Roll out the dough on a floured work surface to a thickness of approx. 3 mm. Cut out hearts (4-5 cm Ø) and place them on 2-3 baking trays lined with baking paper. Bake the trays one after the other in a preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for 8-10 minutes. Take out and let cool down
Beat the egg whites until stiff, add 50 g icing sugar. Pour the beaten egg whites into a freezer bag or piping bag and cut off a small corner. Border hearts with beaten egg white and let them dry for about 30 minutes
Roughly chop the chocolate coating. Melt the couverture and coconut oil in a bowl over a warm water bath. Fill the hearts with the couverture and chill for about 1 hour until the couverture is firm
waiting time approx. 1 1/2 hours