I was very pleased with the "Dressy Chocolate Loaf Cake" from Dorie Greenspan's Baking: From My Home to Yours. (We have some leftovers: I'll try to remember to take a photo of the next slice I eat.) It's a dark, tight-crumbed sour cream chocolate loaf cake, split into three layers and filled with raspberry jam, then frosted with a particularly good and easy bittersweet chocolate frosting.
The frosting is simplicity itself: rig up a double boiler and melt five ounces of chopped semi-sweet chocolate. Then, still working over the hot water, add half a cup of of room-temperature sour cream. Stir gently until the chocolate and cream are thoroughly combined, glossy, and smooth. That's it: no extra sugar or milk or butter or anything of the adulterating sort. The chocolate may seize up at first if your sour cream is chilly, but if you keep stirring, it will sort itself out.
Then you frost the cake with this icing while it's still warm. It's very easy to work with, plenty to cover a largeish loaf cake, and as it cools it firms up into something dense, fudgy, tangy, and not at all insipid or overly sweet. A+. I was thinking that it would be stylish and tasty to make the same cake with a lemon batter rather than all chocolate. Milk chocolate and lemon are sort of blah together, but (as I learned from Italian gelaterias) dark chocolate and lemon are great, and the raspberry would fit right in. What do you think?