Once you have control of Lily.
1: Grab the cooking pot above Dougal.
2: Tell Dougal to attack the string on the large cabinet by the front door to get a new bowl.
3: Tell Dougal someone is at the door, then quickly select the bag of oats in the top right of the screen.
4: Select the prep table and watch the cut scene.
Achievement will follow once this scenario is over.