Preheat the oven to 325°F. Combine cream, puree, and fleur de sel, bring to a simmer over medium heat, stirring occasionally and remove from heat.
In a mixing bowl whisk together the egg yolks and sugar until a pale yellow color is achieved (about 4-5 minutes). Gradually add in the cream to the egg and sugar mixture, mix until smooth. Then pour through a fine mesh strainer into a pitcher.
Divide mixture between 6 ramekins. Arrange in a large roasting pan and pour enough hot water to come halfway up the sides of the ramekins. Cover loosely with foil.
Bake until custard is set around the edges but jiggle in the middle when slightly shaken, about 55-60 minutes. Carefully remove and let cool to room temperature. Then chill for 2 or more hours until ready to serve.
Serve with fresh whipped cream , lime zest and a sprinkle of fleur de sel for garnish.