Preheat the oven to 350°F. Lightly grease six or seven 6-once ramekins and place them into a baking dish that is at least as high as the dishes.
Pour the Dulce de leche into a heavy-bottomed saucepot and whisk in the whipping cream. Make sure to whisk until dulce de leche dissolves into the cream.
In a large bowl, whisk together the egg yolks, egg and vanilla extract.
Pour the first mixture into the eggs and whisk until the mixture is homogenous.
Carefully pour this mixture into the ramekins. Pour boiling water around the ramekins so that the water comes at least halfway up the ramekins. Bake the custards for 30-35 minutes, until the custards are set at the edges but still jiggle in the middle. Let them cool in the pan for 20 minutes, then carefully remove to cool at room temperature before chilling for at least 3 hours.
To serve the brûlées, sprinkle the tops of each of the custards with a thin layer of sugar, then melt and caramelize the sugar using a kitchen torch. Add a second layer of sugar and repeat. This technique builds a crunchy top that is less likely to burn than if you put on a thick layer of sugar.