Eggsy wasn't that bad of a cook, he was just a little clumsy in the kitchen. However, the idea of baking a pie for a holiday he never really recognized was appealing... in its own unique way. Perhaps it was because of the fact there was pie involved and, if he didn't completely butcher the process of putting it together, it was going to be delicious. Helping him along the way was a very patient teacher.
For example, stirring from an angle was something Eggsy never thought about, and yet it made it easier. Goosebumps here and there as Harry gingerly touched his elbow, surprised but not put off by the innocent gesture. "It's a lot better when it isn't from a can, the filling, yeah? I'm actually really excited about eating it."