Toast the fig leaves over a gas flame until they are wilted and caramel colored around the edges, but don’t let them burn. Set aside to cool, then tear them into small pieces.
Heat the cream and milk with half the sugar in a heavy pan set over medium heat. Once the cream begins to boil, stir in the torn fig leaves, remove the pan from the heat and set aside to steep for 15 minutes.
In a bowl, combine the egg yolks, whole egg, salt, milk powder and the remaining sugar and briskly whisk for 1 minute. Fill a large bowl with water and ice cubes.
Return the pan with the cream to the heat and bring it back up to a simmer, then strain the cream through a fine-mesh sieve into a pitcher. Using a ladle, slowly pour some of the hot cream into the egg yolk mixture to warm it and loosen it slightly. Gradually pour the warmed egg mixture into the remaining hot cream in the pan, whisking constantly as you pour. Cook the custard over medium heat, stirring continuously and scraping the bottom of the pan with a rubber spatula or wooden spoon, until the custard thickens enough to coat the back of a spoon. Remove from the heat and place the pan of custard into the prepared bowl of iced water to cool completely, stirring it periodically and being careful not to get any splashes of water in the custard. Transfer the custard to a bowl and chill in the refrigerator for at least 2 hours, or overnight if you can.
Pour the custard into an ice-cream maker and churn according to the machine’s directions. The ice-cream is ready once it has increased in volume, holds the lines from the stirring mechanism and mounds like softly whipped cream. Transfer the ice-cream to a lidded freezer-proof container and freeze for a few hours until firm before serving.