We will start by preparing the marzipan. For that, we add the sugar and water in a saucepan, put it over medium-high heat and bring it to a boil. Once it boils for a minute or so We remove it from the fire. In a bowl, add the ground almonds and gradually add a third of the prepared syrup, stirring at the same time with a wooden spoon. We continue to incorporate the syrup in small quantities and observe that a paste of manageable consistency is made, as it depends on the ground almond that we have.
We make a ball and let it rest and cool for about two hours. Once cold, sprinkle icing sugar on the table and spread the marzipan with the rolling pin until it is 2 to 3 millimeters thick. Then with a skewer we mark the typical lines of the bones and we cut some rectangles about 5 centimeters wide by 6 centimeters high. To give them the shape, we roll them on the stick of a wooden spoon, and we place them standing on a baking tray. We let them dry in this way for at least four hours.
While we prepare the yolk cream. For that, in a microwave-safe glass bowl, add the egg yolks and lightly beat them. On the other hand, in a saucepan we make a syrup with the water and sugar again, over medium-high heat, once it comes to a boil we count three minutes or if we have a kitchen thermometer, it will be when it reaches 105 degrees centigrade. We remove and we are adding the syrup to the egg yolk, stirring without stopping.
We put the bowl in the microwave and we cook the yolk at maximum power for 30 seconds, stopping and stirring, until the yolk is thick. It will be about two minutes or two and a half minutes. We can also cook it in a bain-marie without stopping stirring and being careful not to cut it, this will take us half an hour or so. Once the yolk is dense, we let it cool for a while at room temperature covered with a film glued to the surface so that it does not crust, then we put it in the fridge for two hours so that it takes on body.
Once the bones are dry, we put the yolk in a pastry bag with a narrow nozzle and we are filling the bones with it. Once filled, we prepare a bath glaze with the icing sugar and water and we are putting the bones in it, turning them over with two teaspoons and then letting them drain on a rack until they dry, which will be at least four or five hours depending on the humidity of the environment.