On birthdays, or, Chocolate Coffee Cake with Mocha Mascarpone Frosting

I am not one of those people who "just forgets to mention" their birthday. Every year I think to myself, be cool, Adrienne, it's not a big deal, I'll only mention it if anybody asks me what I'm doing this weekend. And then I never, EVER succeed at keeping my mouth shut. I mean, I don't shout it from the rooftops or tell strangers on the T about it, but if you mention "February 7th" in conversation, I'm going to tell you it's my birthday.

We're well past that now, and I had a very nice party with a delicious birthday cake baked by my non-baking boyfriend. (He's so sweet!) But there are other birthdays in the year, and that's really what we're here to talk about. Today is my mom's birthday (happy birthday, Mom!) and yesterday was my sister's birthday (happy birthday, Julia!). Next week there are some cousins' birthdays, tomorrow there are TWO friends' birthdays but alas, only one party. And this past Tuesday, April 14th, was this blog's first birthday!

And since what's a birthday, really, other than an excuse to eat some cake, let's talk about this tasty specimen, shall we? I made this Coffee-Chocolate Layer Cake with Mocha-Mascarpone Frosting from the April 2009 issue of Bon Appetit for a friend's birthday at the end of March. Like all the best chocolate cakes, the cake itself is light and moist (from the buttermilk) and the flavor is positively miles deep - I finally got some real espresso powder instead of the Maxwell House I'd been using, and I think that has something to do with it.

The frosting, on the other hand, is not what I had hoped. It's DELICIOUS, don't let me sway you from making it at ALL, but if you look at the photo in that link to the original recipe, you'll see why I was a little disappointed. I'm not surprised that it's so light given the 16 ounces of mascarpone cheese, but I'm still not convinced that this is the frosting on the cake on BA's photos. The response to all the why-is-my-frosting-so-light queries in the comments is something along the lines of "the photos are, uh, dark, and we used, uh, high quality cocoa." Hm. Not sure I'm buying it, but I'm going to try again. Either way, even if you pipe the light brown frosting rather messily from a plastic bag with the corner snipped off as I did, and it doesn't look all that pretty, it does indeed taste like a mocha latte. That is to say, really freaking good. Happy birthday, everyone.

Coffee-Chocolate Cake with Mocha-Mascarpone Frosting
adapted from Bon Appetit, April 2009

Cake
2 cups cake flour
3/4 cup natural unsweetened cocoa powder (use the best you can)
1 1/2 teaspoons baking soda
3/4 teaspoon salt
3/4 cup (1 1/2 sticks) unsalted butter, room temperature
2 cups (packed) golden brown sugar
3 large eggs
1 1/2 teaspoons vanilla extract
1 cup buttermilk
4 teaspoons instant espresso powder dissolved in 3/4 cup hot water (don't use instant coffee, the real espresso powder is worth it!)

Frosting
1/3 cup natural unsweetened cocoa powder (use the darkest you can find)
1 tablespoon instant espresso powder
1 1/2 cups chilled heavy whipping cream, divided
1 1/3 cups sugar
2 8-ounce containers chilled mascarpone cheese
Bittersweet chocolate curls (optional) (clearly I didn't make beautiful "curls," but my shards look ok, right?)

Cake

Position rack in center of oven; preheat to 325°F. Generously butter two 9-inch cake pans with 2-inch-high sides; dust with flour, tapping out any excess. Line bottom of pans with parchment paper. I used three 9-inch pans because mine don't have 2-inch sides, so I ended up with a 3-layer cake, which I think is fancier anyway.

Sift 2 cups cake flour, cocoa, baking soda, and salt into medium bowl. Using electric mixer, beat butter in large bowl until smooth. Add brown sugar and beat until well blended, about 2 minutes. Add eggs 1 at a time, beating well after each addition. Mix in vanilla. Add flour mixture in 3 additions alternately with buttermilk in 2 additions, beating just until blended after each addition. Gradually add hot espresso-water mixture, beating just until smooth.

Divide batter between pans; smooth tops. Bake cakes until tester inserted into center comes out clean, about 40 minutes. Mine only took 35 since I used 3 pans and my layers were thinner. Cool cakes in pans on rack 15 minutes. Run small knife around sides of pans to loosen cakes. Invert cakes onto racks; lift pans off cakes and remove parchment. Place wire rack atop each cake; invert again so top side is up. Cool completely. You can make the cakes a day ahead, wrap them in plastic, and store at room temperature - I did!

Frosting

Sift cocoa powder into large bowl; add espresso powder. Bring 1 cup cream to boil in small saucepan. Slowly pour cream over cocoa mixture, whisking until cocoa is completely dissolved, about 1 minute. Add 1/2 cup cream and sugar; stir until sugar dissolves. Chill until cold, at least 2 hours. The mixture will be very dark and may give you false hope about the color of your frosting.

Add mascarpone to chilled cocoa mixture. Using electric mixer, beat on low speed until blended and smooth. Increase speed to medium-high; beat until mixture is thick and medium-firm peaks form when beaters are lifted, about 2 minutes (do not overbeat or mixture will curdle).

If your cake layers are even, good for you. How'd you do that? If not, level the bulbous tops with a long then knife (a serrated bread knife works well). Using a pastry brush, brush off crumbs from cakes. (BTW, best idea ever, and the first time I've ever seen it written into a recipe!) Place 1 cake layer, top side up, on platter. Spoon 1 3/4 cups frosting in dollops over top of cake. Using offset spatula, spread frosting to edges. I always eyeball the amounts between layers and I was conservative since I had an extra layer, but I ended up with extra frosting. Top with second cake layer, top side up, pressing to adhere. Spread thin layer of frosting over top and sides of cake. (Repeat with third layer if necessary) Chill 10 minutes. Using offset spatula, spread remaining frosting over top and sides of cake, swirling decoratively. Top with chocolate curls, if desired. Can be made 1 day ahead and chilled, covered with a cake dome. Let stand at room temperature 20 minutes before serving.