These lemon tarts have a shortbread shell, creamy lemon filling, and buttercream. Fun fact: lemons are believed to be a hybrid between a sour orange and a citron. Subscribe to Science Channel: http://bit.ly/SubscribeScience Check out SCI2 for infinitely awesome science videos. Every day. http://bit.ly/SCI2YT Download the TestTube app: http://testu.be/1ndmmMq