If you're holding a handfasting instead of a traditional wedding, you may want to do something special instead of just having a traditional cake. Sharing a cake with your new spouse is a time-honored tradition that goes back many centuries, so if you're looking for something a bit different, you might want to try something that reflects that history. The idea of the big ostentatious white wedding cake is a relatively new one; in fact, in days gone by, the wedding or handfasting cake was actually quite simple and plain. Sometimes it was brushed with sugar or honey if the bride and groom were well-off, but often it was just a cake with little to no ornamentation.
Originally, wedding cakes were provided by the guests. Each person attending the ceremony brought a small cake, and they put them all in a big pile. Eventually, as enough people arrived, you ended up with a giant heap of cakes. Around the Victorian era, however, that changed, and it became the responsibility of the bride and groom to provide a cake for guests. Now, it seems that the bigger and more elaborate the cake is, the more impressive people see the wedding.
Look at any wedding magazine, and there are three things you see in more photos than anything else. The bride, the groom, and a big honkin' cake. Some of these cakes you see in magazines cost hundreds and even thousands of dollars. If you're willing and able to pay someone an entire paycheck just to bake you a cake, then go for it. However, most people can't do that. If money is in fact a consideration -- as it is for nearly everyone who's NOT in a magazine -- then that's going to have some bearing on what kind of cake you get.
Ideally, you have a really good friend who bakes. Offer to pay your friend for the cost of supplies, and ask her if she would bake you a cake as her wedding gift to you. If she's a professional baker, even better! If that's not an option, find a baker -- a local one, not the one in your chain grocery store -- and explain what you want. Tell them what the theme of your handfasting is, and see if they're willing to work with you. If they aren't willing to work with you to make the cake you want, no worries -- go somewhere else. There are plenty of bakeries out there. If they offer you samples, try them!
One big cake or many small ones? Well, depends. If you have a few flavors you really like, you can certainly make several smaller cakes. Likewise, if you have guests you know have allergy issues, you can work around those. I recently read about a handfasting that had one chocolate cake, one spice one because the best man was allergic to chocolate, a dairy-free cake, and a gluten-free cake. There was literally something for everyone.
When it comes to flavors, try to pick something that everyone will enjoy, without being bland. A spice cake recipe would fit in well with a Medieval, Renaissance or other "themed" handfasting. They're easy to make, they're delicious, and it won't send your guests into a coma from sugar shock. Pound-cake styles are usually a safe bet as well, although they do tend to be heavier on the eggs and butter than other types of cake.
For decorating your cake, if you'd like to avoid gobs upon gobs of pink or white icing, try something a bit more natural. Candied mint leaves or fruits, even edible flowers or sugar-coated petals are perfect. If the bride and groom have a symbol they're using for their union, you can incorporate that as well.
For information on how to make and design your own handfasting cake, as well as how to calculate how much cake you'll need for the number of guests, be sure to check out Nina Callaway's Wedding Cake Guide.