1. Melt butter in a nonstick skillet over medium heat. Add sugar, rum, and cinnamon; stir to combine. Add banana; cook 1 1/2 minutes. Remove from heat.
2. Spoon 1/2 cup ice cream into each of 4 bowls. Top each serving with about 2 tablespoons banana mixture and 1 teaspoon almonds. Serve immediately.