Place the brownies and ice cream in chilled bowls and set aside in the refrigerator. Thaw and strain the frozen cherries. In a medium saucepan, whisk together the juice from the frozen cherries, brandy and the cornstarch. In a saute pan, over high heat, melt the butter and sugar. Add the fresh and frozen cherries. Carefully pour in the brandy mixture. If it does not burst into flames spontaneously, ignite with a match. Gently swirl the pan. Soak the sugar cubes in the rum. Pour the cherries around the ice cream. Top with a glob of marshmallow cream and plant a sugar cube on top. Light the cube with a match.
Marshmallow Cream: In a small saucepan fitted with a candy thermometer, bring the water, corn syrup, and 3/4 cup of the sugar to 246 degrees F (firm ball). In the meantime, in a completely clean, dry mixing bowl, with an electric mixer, whisk the egg whites, salt, and cream of tartar until creamy and foamy, about 2 minutes. Still whisking, sprinkle in the remaining 1 tablespoon of sugar and continue to whisk until the whites hold very soft peaks, about 2 minutes. While mixing on slow speed, carefully drizzle in the hot syrup. Turn the mixer to high and whisk until thick, fluffy, and just warm, about 7 minutes. Turn the mixer to low and whisk in the vanilla.