Begin by preparing the raisins at least one day before you plan to serve the ice cream. Combine 1½ cups raisins with 5 tbsp dark rum in a bowl and allow them to soak overnight, or for as long as possible.
This soaking period is essential, as it allows the raisins to plump up and absorb the rich rum flavors that will define the finished ice cream. While the raisins soak, prepare your 2-quart freezerproof container and make sure it’s clean and ready for the final mixture.
When ready to proceed, separate 4 large eggs, placing the yolks in one small bowl and whisking them with a fork until blended.
In another bowl, use a handheld electric mixer to whisk the egg whites until they resemble clouds. While continuing to whisk at maximum speed, add ½ cup granulated sugar one teaspoon at a time until the mixture becomes stiff and glossy—this process typically requires several minutes.
In a separate bowl, whip 1¼ cups heavy cream until soft peaks form, then gently fold this into the egg white mixture until smooth and fully combined.
Complete the ice cream base by stirring the whisked egg yolks and the rum-soaked raisins into the whipped cream and egg white mixture, including any remaining liquid rum from the soaking bowl.
Transfer this combined mixture to your freezerproof container and place it in the freezer for a minimum of 24 hours. When ready to serve, remove the ice cream from the freezer 10 minutes before scooping to allow it to soften slightly, making it easier to serve while maintaining its texture.
