Make a caramel out of the 1 cup sugar. Stir continuously in low medium heat until there is no visible grain. Pour into round baking pan (8 inches diameter) and let it dry until it cracks. Leave as is until ready for the mixture.
Preheat oven to 300 degrees. Fill a rectangular pan half full with water and place pan in bottom rack of oven. In a bowl, slightly beat egg yolks. Add both cans milk and vanilla and stir until thoroughly mixed. Pour mixture through a small sifter into the round baking pan.
Arrange baking pans in a way that the one with water is on the bottom rack and pan with mixture is on the top rack. Bake for one hour. When done, remove from oven. Let it cool. Refrigerate. Serve when cool.
