I love making birthday cakes. While I don’t have a problem with having a little dessert every day, I do think there’s unique joy in having something made just for you on your special day — hopefully with your tastes and preferences in mind.
This cake was for my father-in-law’s birthday. He’s one of the most non-picky eaters I know; but while he eats everything, he especially likes chocolate and nuts. This was for a small family celebration, so the cake is quite small: two 6-inch layers. If you want to make it into a double layer 8-inch cake, refer to the original chocolate cake recipe and make 1.5-2x the frosting (this recipe makes a generous amount; I gave this cake a fairly thick layer and still had enough leftover to frost 20 mini cupcakes).
Some notes on the frosting: I’ve had mixed experiences with Swiss Meringue Buttercream (SMBC); although I’ve made it sort of successfully in the past, to be honest I didn’t really like the flavor of it before — it just tasted like sweet butter. (Which I guess it is.) This time was different, for a couple of big reasons:
- I borrowed my sister-in-law’s stand mixer. It still took awhile to make the frosting, but my hand didn’t feel dead at the end. My previous attempts at SMBC were with a hand mixer; it’s possible that way, but the stand mixer really does make the process way easier and more enjoyable, IMO.
- Peanut butter and cream cheese. They go so well together, and in this case they combine to make the fluffiest, silkiest, and most tasty peanut butter icing I’ve ever had. I’m generally not a huge icing person, but I could have eaten it straight with a spoon. The brown sugar added a little something something too; a nice depth of flavor that reminded me of honey roasted peanuts. Yum.
I’ve read a lot of SMBC tutorials and recipes (see here, here, and here just for starters), and they vary pretty widely on the ratio of egg whites to sugar to butter. I aimed somewhere in the middle, and chose to be conservative in the sugar amount since I prefer my icings not too sweet. There also seem to be varying opinions on how much cream cheese works in this type of icing, and I know some people have trouble with cream cheese SMBC breaking because of the water content of the cream cheese. I went for a half-butter, half-cream cheese ratio, and kept a couple extra tablespoons of butter on the side in case I needed it to help emulsify the mixture. In the end, I did end up using the extra butter. I also refrigerated the icing for about 10 minutes during that scary curdling stage, then just kept whipping at a low speed and it eventually came together. My advice is to just be patient and not panic; read a few tutorials on how to fix broken buttercream ahead of time so you know what to do if and when your icing reaches that stage. This is honestly one of the tasiest frostings I’ve ever made so I do hope you give it a try!
To add a little texture, I made some peanut brittle for garnish. This was my first time making peanut brittle, which was exciting because I got to use my brand-spanking-new candy thermometer! Last year I attempted making soft caramel candies a couple of times and failed; later I realized it was because my thermometer was a good 15 degrees off…basically the difference between delicious and burnt. The lesson here is: check your thermometer’s calibration by putting it in a pot of water and bringing it to a boil. It should register 212F / 100C when the water boils. Hopefully that’ll save you a few burned batches of sugar!
Peanut Butter Chocolate Cake with Maple Peanut Brittle
Makes one 2-layer, 6-inch cake
For the Midnight Chocolate Cake
A half batch of this recipe, baked in two 6-inch pans, with the following changes:
- Use half all purpose, half cake flour
- Use black cocoa for the cocoa powder
- Start checking for doneness around 25 minutes
For the Maple Peanut Brittle
Recipe adapted from Layered: Baking, Building, and Styling Spectacular Cakes
- 55g / 4 Tbsp unsalted butter
- 110g brown sugar / 1/2 c (I used light)
- 1/4 c maple syrup
- 1/4 c light corn syrup
- Heaped 1/4 tsp baking soda
- 1/2 t kosher salt
- 150g / 1 c roasted, unsalted peanuts
For the Peanut Butter Cream Cheese Swiss Meringue Buttercream
- 135g egg whites, room temperature
- 220g light brown sugar
- 150-180g butter, cut into cubes, at cool room temperature
- 150g cream cheese, cut into cubes, cool room temperature
- 1/2 Tbsp vanilla extract
- Smooth creamy peanut butter, such as Skippy or Jif, to taste (I used three large spoonfuls)
- Pinch of salt, to taste
- Chopped roasted, unsalted peanuts
- Various chocolate candies (I used bite sized Snickers and some white chocolate covered almonds)
Make the Maple Peanut Brittle:
- Line a sheet pan with parchment or a Silpat and set aside.
- Combine the baking soda and salt in a small bowl. Have your peanuts measured and ready to go as well.
- Combine the butter, brown sugar, maple syrup, and corn syrup in a medium saucepan. Cook over medium-high heat, stirring occasionally with a silicone spatula, until the mixture reaches 298F / 149C on a candy thermometer. Remove the pan from the heat and stir in the baking soda and salt. Fold in the peanuts and pour the mixture evenly onto the prepared baking sheet (work quickly as it does harden rather fast).
- Let the brittle cool completely (about an hour) before breaking in pieces to use for decoration. Store leftovers, layered between pieces of parchment paper, in an airtight container.
- Note: To easily clean your sugar work pans, fill with water, cover, and bring to a boil for several minutes. It’ll melt the sugar right off.
Make the Peanut Butter Cream Cheese Swiss Meringue Buttercream:
- Place egg whites and brown sugar in a heatproof bowl (such as the bowl of your stand mixer) and whisk to combine. Set bowl over a pot of just simmering water to create a double boiler and whisk until mixture reaches 140-160F. Don’t allow the bottom of the bowl to touch the water.
- Transfer the bowl to a stand mixer fitted with the whisk attachment. Whisk the egg white-sugar mixture on low for a couple of minutes and gradually increase the speed to medium high. Continue whisking until the meringue reaches glossy stiff peaks and both the meringue and the bowl are at room temperature (about 10 minutes).
- Switch out the whisk for the paddle attachment. With the mixer on low, add the butter one cube at a time. Wait until the butter is completely incorporated before adding the next cube. When the butter is incorporated, repeat with the cream cheese.
- Continue mixing on low until the mixture is smooth, then add the vanilla, a pinch of salt, and peanut butter a spoonful at a time (to taste). Taste and add a touch more salt if the mixture tastes too sweet. Mix on medium speed for a couple minutes, or until the buttercream is smooth, silky, and fluffy.
Assemble the cake:
- Level your cakes if desired. (Note that this chocolate cake is very tender and moist, so I highly recommend working with them chilled.) Set your first cake round on a cake board and spread a generous amount buttercream evenly over the top, followed by a sprinkling of chopped peanuts. Set the second cake round on top and spread a thin coat of buttercream over the top and sides to trap all the crumbs. Refrigerate until buttercream is firm, about 20 minutes.
- Add a thicker layer of buttercream over the top and sides, using an offset spatula and icing scraper for evenness.
- To get the “rustic” look, use an offset spatula or back of a spoon to create random swoops.
Top with chopped peanuts and peanut brittle if desired. If you’re not serving the cake right away, store in the refrigerator but bring to room temperature before serving. Just before serving, garnish with peanut brittle and candies. (Don’t put the brittle on too soon or it may soften and weep.)