I realize you've probably done it by now, but it's down to personal preference. Making it ahead will allow the flavors marry. Another very traditional dessert is Tipsy Laird (basically an English trifle with whisky replacing the usual sherry), black bun (fruitcake), or anything with raspberries or rhubarb. Steamed puddings are also very traditional, as is clootie dumpling.

Thanks so much everyone. I torched the oatmeal, so I'll be using granola instead (thanks Verdigris). mrslarkin, I scored a lame-o 3 on the haggis game.

Yum. Thanks for teaching me about this. I wonder. . .does it have to be for dessert? Can't I have some for breakfast. . .please, please, please?

My mom always made this ahead of time, letting the whisky meld with the raspberries

I pulled this recipe when it was first printed. Have to admit that I still haven't made it, but it sure sounds like a good variation! http://www.epicurious.com/recipes/food/views/Chocolate-Cranachan-109499

Googling this recipe I saw that the traditional way of serving this is to place bowls of the ingredients on the table and let each diner prepare their own in tall dessert glasses. That would do away with the sogginess you fear but would still allow the make ahead of the base ingredients.

I have made similar dishes a couple of hours ahead but I used granola instead of just toasted Oatmeal, Some of the crunch still remained after the sitting. I have also used broken oatmeal cookies in place of the Oatmeal. That works very well.

A quick search on the google brought this up: http://www.scottishrecipes.co.uk/cranachanrecipe.htm Sounds yummy! I think it'll be fine if you assemble before dinner - that doesn't seem too long.

Oh, and make sure you visit their other website to play the Whack the Haggis game. I scored a whopping 29!