You'll need about 1 3/4 cups of the sweet potato, mashed plain, that you can accomplish in a couple ways - baking them or using the microwave to speed up the process. Since you won't be needing the skins, the microwave does an excellent job and the soggy skins won't be an issue - but if you're already using the oven for another project, toss them in for about an hour. I did this the night before since we had to turn the oven on for dinner, then kept the mashed 'taters in the refrigerator.
Before we started assembling the remaining ingredients for the cake, the raisins, which are added near the end of mixing, need to first take a dip, but they won't be swimming in water. To give them a juicy spark, the little guys are covered with a couple tablespoons of dark rum and sit happily until called for.
There isn't much flour in this "cake" - only a cup used, which bound the mashed sweet potatoes together, along with a few eggs, brown sugar, a couple tablespoons of melted butter and a can of light coconut milk. We use a combination of all-purpose and whole-wheat pastry flour to work in a bit of whole grain, but use completely all-purpose if you like. Slightly sweet fresh grated nutmeg (please do yourself a favor and find whole nutmeg to use - grating them fresh with a microplane, or even the small holes on a box grater, makes all the difference!) is also tossed into the batter as the warming spice of choice. Not everyone is a fan of nutmeg, especially when it is overused on a glass of Eggnog, and if that is the case for you, think about switching it out for ground ginger or even cinnamon - it will be a different profile, but good nonetheless.
Stirring the plumped raisins, along with any extra booze left behind, into the batter, the thick mixture is scraped into a springform pan and has one more addition before it is ready to bake. For a sweet, crunchy topping, shredded coconut, a couple scoops of brown sugar and a hint of cinnamon are jostled together, then sprinkled as evenly as possible over the top. There is a 15 minute gap on the bake time as the moisture level from the potatoes will play a factor into doneness of this cake - check it at the earliest time by sliding a thin knife into the center. If there is still sticky batter clinging to the knife, give it more time, checking every 5 minutes or so - the knife should come out pretty clean.
Between the brown sugar, sweet potato and raisins, I began to wonder if the sweetness level would be off the charts, but I was surprised to find that just wasn't the case - I think the coconut milk suppressed any cloying aspects to instead let the inherent flavors come through and dance on the tongue. The cake is dense, but not heavy - kind of like if you mashed a moist cake with a luscious cheesecake. The rum-drenched raisins hit the spot as we found them in each forkful of this pudding cake, but don't be tempted to tamper with them... go out and buy a little nip from a liquor store if you don't have a bottle.
Sweet Potato Pudding Cake