In a medium bowl, beat the cream cheese with a hand-held electric mixer on medium speed until very smooth, about 1 minute. Add the butter and beat until smooth, about 30 seconds. Beat in the lemon zest, lemon juice, and vanilla.
On low speed, gradually add the confectioners' sugar, beating until smooth. Increase the speed to high and beat for just a few seconds, until the frosting is smooth and fluffy. Don't over beat or you may thin the frosting.
Notes
Makes about 2 cups (or a little more frosting than you’ll need for the cupcakes)