In a medium saucepan, melt margarine. Remove from heat and stir in cocoa, sugar and salt until they dissolve. Stir in evaporated milk and syrup until well combined. Stir in cornstarch mixture. Return to heat and bring to a boil. Cool sauce and stir in vanilla. Serve warm over ice cream. Can be refrigerated and warmed for future use.
Recipe Courtesy of Food Network Kitchens