Preparation

• Finely grate the truffle and set it aside for later.
• Grate the cheese and reserve it for afterwards.
• Using a brush, generously coat the molds with softened butter. Ensure all internal surfaces of the mold are covered. Once coated, place them in the refrigerator for at least 10 minutes to allow the butter to solidify.
• It is recommended to coat the molds starting from the center of the base upwards to the edges, to facilitate easy unmolding.
• Boil the potatoes with their skin on until they are fully cooked, approximately 20-25 minutes, depending on the size of the potatoes.
• Carefully separate the yolks from the whites and set them aside in different containers.
• Preheat the oven to 180ºC for at least 30 minutes. Use heat from Above and Below with ventilation to ensure even temperature distribution.
• Place the tray on the lowest rack of the oven.
• Peel the potatoes and cut them into small pieces.
• Put the potatoes in a bowl and mash them with a manual whisk until you achieve a coarse puree.
• Do not use the electric mixer; instead, if you have one, pass the potatoes through a food mill.
• Pass the mashed potatoes through a chinois strainer and with the help of a silicone spatula, gently press to achieve a finer purée.
• Transfer the purée to a saucepan and heat it over low heat, stirring constantly.
• When the purée is hot, add the butter in pieces and the milk, stirring until the butter melts and everything is integrated into a smooth purée.
• Add the nutmeg, freshly ground black pepper, and, if you prefer, grated truffle or a little grated cheese; do not add too much cheese, as it is meant to be a delicately flavored potato purée.
• Once well mixed, remove the saucepan from the heat and add the egg yolks. Stir to integrate them and set aside.
• Before whipping the egg whites, bring a small pot of water to a boil to generate steam during baking.
• In another container, whip the egg whites to stiff peaks until a firm consistency is achieved.
• Add a small amount of whipped egg whites to the mashed potatoes and stir vigorously with a hand whisk to start the mixture.
• Add half of the whipped egg whites and stir with a "cat's tongue" spatula very carefully and slowly, from the edges clockwise, while turning the bowl counterclockwise with the other hand.
• Once the first half is incorporated, add the remaining egg white and repeat the previous procedure.
• Fill the molds up to three-quarters of their capacity with the prepared mixture.
• Bake the molds in the lower part of the oven and place a pot with boiling water next to them to generate steam during baking.
• Bake the large molds for about 30 minutes.
• Bake the individual molds for 15-20 minutes, depending on the size of the molds.