Beat the eggs together with the sugar and vanillas, then add the melted lard.
Separately, add the baking soda and ammonium bicarbonate to the yoghurt, stir and once effervescent, add it to the egg mixture, then stir again.
Sift the flour in a tray, make a well, pour the mixture in it, knead a medium-soft dough. Pipe out cookies using a pastry bag.
Bake in a preheated 356°F (180 °C) oven to a light golden color. The longer the cookies sit, the softer they become.