This cake is so wildly simple to make, with a brief and uncomplicated ingredient list, that it's hard to believe how sophisticated the result is. With a delicate top layer that shatters like a brownie and a moist, chewy interior studded with black walnuts, it's just as good without the frosting or with a dollop of lightly sweetened whipped cream. It comes from a vintage cookbook of historical Maryland recipes. —Posie (Harwood) Brien
one 9" round cake
For the cake
(4 ounces) unsalted butter, at room temperature
(7 ounces) granulated sugar
(2 1/8 ounces) all-purpose flour
chopped black walnuts (or regular walnuts)
For the frosting
unsalted butter, softened
(4 ounces) confectioners' sugar
hot brewed coffee (use hot water or warm milk if you don't want coffee flavor)
Preheat the oven to 375 degrees F. Grease a 9" round cake pan and line it with parchment paper.
Melt the chocolate and set aside to cool slightly.
Cream together the butter and sugar until very pale in color and fluffy. Add the eggs one at a time, beating well after each to incorporate it fully.
Add the vanilla and mix well. Fold in the cooled chocolate and mix.
Add the flour and salt and mix until just combined. Don't overbeat the batter here. Fold in the chopped walnuts.
Scrape the batter into your prepared pan and smooth the top. Bake for about 25-30 minutes, or until the top is very puffy and a tester inserted into the center only has a few crumbs clinging to it, not wet batter.
Remove the cake from the oven and run a knife around the edges to loosen it, then let the cake cool fully before turning it out of the pan and frosting it.
For the frosting: Beat together the butter and sugar, then add the cocoa and hot coffee and beat until fluffy. PRO TIP: This makes just a very thin layer of frosting, so you can double the amounts of everything if you want a thicker layer.
Spread the frosting over the cake, slice, and serve.