Jez felt her heart sink slightly. Her mother wasn't exactly the let's-bake-cookies-together type mum, and she hadn't been let near the kitchen anyway - her parents believed the poor house elves were responsible for cooking - so her culinary experience was non-existant. But there was a first time for everything, right?
Okay ... mix up the ingredients first. Jez put everything into a bowl, and then remembered seeing the Head Boy put bottles in his pocket. She frowned at him. Was he keeping an important ingredient back?