1. In a medium saucepan, combine rum, raisins, and sugar. Bring to a boil over medium-high, remove from heat, and let cool completely, 30 minutes.

2. In a food processor, combine bananas and condensed milk and process until smooth, 2 minutes. In a large bowl, using an electric mixer, beat cream on high until stiff peaks form, 2 to 3 minutes. With a rubber spatula, gently fold banana mixture into whipped cream. Fold in rum-raisin mixture. Pour into a 5-by-9-inch loaf pan, cover with plastic, and freeze until firm, about 8 hours (or covered, up to 1 week).