Preheat oven to 180 °C (convection). Separate eggs. Mix egg yolks with flour, butter, sugar and cocoa into a smooth dough, first with the dough hook of the electric hand mixer and then with your hands.
On a floured surface, roll the dough out thinly; if the dough sticks, add a little flour. Punch out heart shapes and place them on a cookie sheet lined with baking paper.
With a knife, cut the side or bottom and make a small slit (that would fit on the rim of a glass or cup). Bake for about 10 minutes in the pre-heated oven. Allow to cool and serve on the glass rim of a TASSIMO Carte Noire Caramel Macchiato.