Place chocolate in a 2 cup measure. Micro-cook, uncovered, on 100% power for 1 1/2 to 2 minutes or till melted, stirring once. Stir in corn syrup and sweetened condensed milk. Micro-cook, uncovered, on 100% power for 30 to 45 seconds or till heated through. Stir in vanilla. Serve warm atop ice cream. Sprinkle with peanuts. Arrange quartered banana around ice cream.