Aim for the corner of the house.
Power Activation Point
Once your bird is near or has killed the first piggy, activate the jedi power towards the top. You will knock the base off destroying the first house. And you will send some wooden blocks flying towards the back. The goal is to have the wooden blocks land on the metal part of the catapult.
First Shot Result
Once the catapult is launched from the flying wooden blocks, the purple ammunition will kill destroy the second house to the right, netting you with the full 3 star mastery.