Boil the condensed milk in the can in a pressure cooker for 45 minutes or in a normal saucepan for 2 hours.
Let cool down for at least 5 hours before opening the cans. Then stir the milk well with a wooden spoon. Gradually add the egg yolks, stirring constantly. Beat egg whites out of the egg white and fold in carefully. Serve the custard sprinkled with almond slivers.