AI tried the wilton vanilla cupcake recipe but my cupcakes have an after taste of eggs? Does anybody know why?

AAre they still warm? If yes, let them cool and retry. If they are cool, I would suggest that they may have too much egg. Many cookery books would suggest to weigh your egg once cracked to get the right amount. Otherwise you may not have cooked it through enough or your mix want blended enough and you have clumps of egg. Fat less sponges with whipped egg/egg white sometime smell of egg before they cool so it really does depend on your recipe and the bake.