My best friend's birthday is coming up and for the first time in a couple of years we won't be able to celebrate together because he graduated and moved across the country. I want to send him something creative, so I'm going to put together a little package of dry ingredients that he and his housemates can use to bake a cake (similar to those cute, prepackaged jars of hot chocolate or soup mix that just need water or a few fresh ingredients most people have on hand). I've been perusing my favorite food and baking blogs and I've come across some wonderful cake recipes, but they all sound a little bit too complicated for him--they'd require finding special perishable ingredients or tools and techniques that he wouldn't know how to use. Ideally, I'd like to be able to find a recipe where I could ship all the dry ingredients, and he'd just have to add something simple; no more than eggs, milk, butter, or oil...and then bake it up! I would include instructions, naturally.
Does anybody have a delicious, simple, foolproof recipe that could work for this? Much appreciated!