Pining for a Book Read Long Ago

Hello, all! For some reason, today I started thinking about a book I read about 12 years ago(...really, who remembers books they read when they were six?). I'm not sure if the book is well-known or not, but I do remember certain parts of the book. Note: this is a chapter book, not a picture book.

This book features a young boy staying in a hotel with his mother (and possibly his father). His mom paints pictures inside matchboxes for a living, and the pictures are extremely detailed. One night, in the hotel, the boy sneaks out of his hotel room. This leads to him being kidnapped by the parents of another boy in the hotel. They dress him up in fancy clothes and force him to eat 'spag'.

It's really a rather odd story, but I remember it being really enjoyable. And yes, that's barely any information. Sorry.