In a large mixing bowl, cream butter and sugar. Add egg whites,one at a time,beating after each addition. Beat in vanilla. Combine the flour, baking powder and salt; add to creamed mixture and beat. Grease cupcake pan or fill cup cake liners 2/3 full. Drizzle strawberry syrup on top and use a toothpick or knife to swirl into batter. Bake in a preheated 350 degree oven for 25 minutes. Cool. Turn out on a plate. In a small mixing bowl, combine Cool Whip and confectioners' sugar and beat on high for 30 seconds. Frost cupcakes and candy hearts on top and sprinkle with colored sugar.