For my son's birthday, we went to La Caille for dessert. (Which we often do because we get to enjoy the atmosphere without eating snails & a lot of the desserts catch on fire! FUN!) Afterward, we presented him with this huge candy gram. He loved the treats & the money at the end & I liked being able to sneak in a little advice about growing up. The gram is made from Reynolds Freezer Paper--which comes on a huge roll, so you can make your message as long as you want. This paper can be purchased at grocery stores & it has a wax backing (so your marker doesn't seep through to the table when you're writing).
PS - If you're just having dessert at La Caille, (or the fancy restaurant in your area) let them know when you make your reservation. They take all the extra dishes & utensils that won't be needed off the table before you come.