Leche Flan

8 egg yolks (reserve egg whites for "lengua de gato" cookies)
2 cups heavy cream
1 can condensed milk
1 tsp vanilla extract

1/4 cup granulated white sugar (for the caramelized tops)

rind of one key lime or dayap (citrus aurantifolia)

16 2 oz. ramekins or 8 4 0z ramekins
kitchen torch