- 1 vanilla bean, split lengthwise
- 1 quart whole milk
- 4 cups sugar
- 1 large egg
- 8 large egg yolks
- 1/2 cup sugar
- 1/2 teaspoon light corn syrup
- 2 tablespoons water
- Scrape seeds from vanilla bean into a large heavy saucepan and stir in pods, milk, and sugar. Bring mixture to a gentle simmer, then place a small saucer upside down in pot to keep mixture from sticking to bottom or forming a crust. Cook over very low heat, stirring occasionally, until thick and brown, about 2 1/2 to 3 hours. Cool.
- Preheat oven to 325° F. Place eight 6-ounce ramekins in shallow baking pan. Combine sugar, corn syrup, and water in small saucepan with pouring lip. Stir over medium heat until sugar dissolves. Increase heat and boil without stirring until deep amber color, occasionally brushing down sides of pan with wet pastry brush and swirling pan. Immediately pour caramel into ramekins, tilting and rotating ramekins to coat bottom and rewarming caramel over medium heat if it gets too thick.
- Whisk together egg and yolks in large bowl. Whisk in dulce de leche. Strain mixture through sieve into large measuring cup and pour into ramekins, diving evenly.
- Place baking pan in oven. Pour enough hot water into pan to come two-thirds up sides of ramekins. Cover pan tightly with aluminum foil and bake 30 minutes. Tent foil to vent steam and continue to bake 10 to 15 minutes, until flans are set around edges but still slightly wobbly in centers. Using metal spatula, transfer flans in ramekins to rack; cool 30 minutes. Chill at least 3 hours and up to 2 days. To unmold flans, run a small knife around edges to loosen. Invert onto plates.