I've sat down to write this post at least two dozen times in the past couple weeks. Somehow, no matter what I do nothing comes out on the page. I could have moved on to any number of other recipes, but my funny little brain insisted on sharing this one first.
I guess it's appropriate. Mike had been requesting this cake for months—since I made Maple Mousse Cakes, in fact, and I see that that was over a year ago now. Cake scraps, of course, are one of the best parts of cake making, and Mike is well aware of that fact. It doesn't take very long after a carrot cake has cooled to find him lingering at the periphery of the kitchen offering to help me frost it. The mousse cakes, cut out of a very thin layer of sheet cake, provided all sorts of tasty scraps, and Mike declared the walnut cake base perfect just as it was.
I, however, am an unapologetic fiddler. I see recipes and can't help but tweak them; I make notes in the margins of magazines and cookbooks, lists of dates marking the different changes I tried; after a few bites of any new meal I'm already thinking about what I can do next time to take it that little bit closer to perfection.
The trouble was ... I couldn't think of what to do with that walnut cake. I thought about a syrup or glaze like so many simple, rustic cakes, but nothing seemed to be a good fit. Mike said it would be delicious as is, but that seemed a little bit too rustic. I set the recipe away in the back of my brain and started worrying about other things, like what to do with those 6 pounds of marionberries in my freezer or what kind of sausage we should make next (Oh, yes, we've started making sausage from scratch now—more on that later).
Finally I had a breakthrough. Unsurprisingly, much of the credit goes to Deb over at Smitten Kitchen. An online friend mentioned something about Hazelnut Brown Butter Cake, and when I clicked the link everything fell into place. How could I have forgotten chocolate?
Ganache it was.
That very evening, I got to work. I made a few changes to my original recipe: omitting the bourbon, browning the butter (because when is that a bad idea?), and beating the egg whites to further lighten the crumb. Mike still says it would be fine without the ganache, but with it, it's nearly perfect. The cake is moist and tender, with a robust walnut flavor that is set off by the brown butter. The ganache is velvety and rich—and just enough to keep from overwhelming someone (like me) who is frankly on the fence about walnuts most of the time.
Of course, that doesn't mean that I wasn't already making plans for the next one.
Walnut Cake with Bittersweet Ganache
Note that this recipe makes enough batter for one ten inch layer (or a very thin layer in a 13"x18" rimmed sheet); one eight inch and one six inch pan can be used instead if you prefer.
For the cake:
6 ounces butter (1½ sticks)
4 ounces walnuts (1 heaping cup)
5 ounces unbleached flour (about a scant 1¼ cups)
½ teaspoon salt
1½ teaspoon baking powder
5 ounces white sugar (about ¾ cup)
2 ounces brown sugar (about ¼ cup packed)
3 large egg whites
¾ cup milk
For the ganache:
4 ounces bittersweet chocolate, chopped
¼ cup heavy cream
Preheat the oven to 350ºF with a rack set in the center of the oven. Butter one ten inch round pan (or one 8" and one 6" pan). Line the bottom of the pan with parchment, butter the parchment, and set the pan(s) aside.
Brown the butter in a medium saucepan over medium heat, stirring occasionally until the milk solids are evenly brown and the butter is very nutty smelling, 5-8 minutes. Set aside to cool.
Finely grind the walnuts in a food processor, being careful not to over-process. Add the other dry ingredients (including the sugars) and pulse to combine.
Whip the egg whites to soft peaks. Transfer the dry ingredients to a large bowl with the milk. Stir just to combine, then add the brown butter and stir until well mixed. Carefully fold in the egg whites. Spread the batter evenly in the pan(s). Bake until a tester inserted in the center comes out clean, 50-55 minutes (35-40 with smaller pans).
Cool in the pan for 15-20 minutes, then run a knife around the edges to loosen and invert onto a rack. Remove the pan and the parchment, then set right side up to cool completely.
Meanwhile, make the ganache. Heat the cream to a boil on the stove or in the microwave; pour over the chocolate and let sit for a minute or two. Stir until very smooth. (Note: if it ends up being too thick with this method, you can transfer the mixture back to the stove on very low heat or microwave in five second bursts, until smooth and loose enough to pour).
Arrange the cake(s) on a plate and pour the ganache over. Use an offset spatula to spread the ganache in an even layer over the top, letting it drip, more or less as to your tastes, over the edges of the cake. Let the cake sit at room temperature to firm up.
Note that if you will be eating your cake in more than the next day, the ganache needs refrigeration.
Serves about 12