A Charlie and Lola picture book all about parties, by Lauren Child.

It's Charlie's birthday and he has invited all his friends and Lola to an especially scary, hairy monster party - but Lola has other ideas! Not only does she make PINK fairy cakes for his friends, she opens his cards and presents too. Lola says, 'Oh I LOVE birthday parties!' How can Charlie explain to Lola that it is actually HIS party?