There's a spark

Similar to the other achievements, this requires you to serve the correct drinks to both Gala & the Vampire. When Gala asks about finding the recipe, don't worry if you get it slightly wrong, you're meant to test things with him initially. Just input one of the ingredients he asks for and you'll be okay.

The only moment of note is when he desperately needs his drink (you'll know when) which requires serving "Gala Had" which is Tea/Milk/Ginger