mix 10 egg yolks with condensed milk but dont throw away the empty milk can as yet, fill it with water until can full and mix all together. until you get the soft texture set it aside.
if you are lazy, you can buy premade one from the supermarket. otherwise, as follow:
get the rest 2 eggs and get the yolks mix it with 250g margarine and 200g flour. use your hand and treat it like a bread dough, punch it, kick it with clean feet if you wish so until form. use your own judgement, if you think it's too soft, add more flour.
once good to go, get the leftover margarine and smear it to the pyrex or whatever. now spread the dough around, not too thick but not too thin either. put it in the oven for good 15-20 mins till it dry.
once dough is cooked, pour the filling and put it back to oven on 180 degree. leave it and poke it occasionally not with your hand but with fork or needle stick. if the tip is clean then it's ready.
you can serve it hot or cold.