In a large saucepan combine the pineapple, 1/2 cup sugar, and 6 tablespoons rum, bring the mixture to a boil over moderate heat, stirring until the sugar is dissolved, and simmer for 5 minutes. Strain the pineapple mixture through a fine sieve into a bowl, reserving pineapple solids.
Scoop the ice cream into a large bowl and chop into chunks with a large spoon. Allow the ice cream to soften at room temperature until it can be easily creamed together but is not melted.
Add the reserved pineapple solids and stir to combine. Freeze for 2 hours then stir the ice cream and then freeze until firm. The ice cream keeps, covered tightly and frozen, for up to 1 week.
Pat the pineapple shells dry with paper towels and freeze them, wrapped well in plastic wrap, for 1 hour. Pack the shells with ice cream, mounding the ice cream and smoothing the surface, and freeze the filled pineapples, covered with plastic wrap for at least 24 hours.
In metal bowl combine egg whites and granulated sugar, set the bowl over simmering water, and stir the mixture until the sugar is dissolved. Remove the bowl from the heat and with an electric mixer beat the meringue until it holds stiff glossy peaks. Working quickly, cover the ice cream in each pineapple with a smooth layer of meringue. Transfer the remaining meringue into a pastry bag fitted with a small star tip and pipe it decoratively over the pineapples. Sift the confectioners' sugar lightly over meringue, broil the pineapples in batches for 30 seconds to 1 minute or until the meringue is golden and serve them immediately. Yield: 8 servings
Recipe courtesy of Gourmet Magazine