In a large mixing bowl, combine sweetened condensed milk, Malibu rum, pineapple extract, coconut extract and fleur de sel; whisk until blended.
In a chilled bowl of a stand mixer with a chilled whisk attachment, pour in cold cream; process on high speed until stiff peaks form. Add half of the whipped cream into milk mixture and gently fold in until fairly well mixed. Add sweetened coconut flakes and stir again.
Add the condensed milk mixture into the remaining whipped cream and fold once again before transferring to a chilled loaf pan. Using a spatula, level it out, cover with plastic wrap and transfer to the freezer until hardens, about 7 hours. Makes 4 pints/2 liters.