Freezable custard?

I am in the process of creating a couple new types of Christmas goodies, and need a recipe for a custard-type filling that can be frozen, then thawed when ready to eat. Somehow they have to be transported from Columbus OH to Indy, and unless they can be frozen, they will not survive the trip (the driver, my brother, will eat them all along the way!)

I lined a tartlet pan with a cream-cheese based pastry crust, added some violet jelly-coated candied peel and fruit, then baked them. To make them perfect, I would love to have a vanilla or citrus flavored custard to spoon on top. Regular custard just doesn't freeze well, and none of the pre-packaged ones that I have tried are any good.

Help?