Saturday, February 13, 2010

Peanut butter-chocolate mousse cake

Tomorrow is Valentine's Day! That day of all days when I try to convince Allen that I can cook a full meal, one with more than two food groups. Since that generally ends in failure (although Huey the Pup will eat well, as long as he likes char), I'm going to stick with a blog entry about something I know: baking.

I'm not sure what wine pairs with peanut butter. Schlitz, maybe.

One of our two small wedding cakes was a chocolate cake filled with peanut butter mousse, and covered in chocolate ganache. Both cakes - the peanut butter one, and the lemon-coconut cake - were incredible. Bob, of Decatur's Pastries A-Go-Go, who baked our cakes, made a 6" version with which I surprised Allen on our first anniversary.

Several bakeries in Atlanta offer peanut-butter mousse cakes. I've never been able to figure out how the mousse is made, since peanut butter won't fold nicely into beaten egg yolks or whipped cream. Most recipes online are actually pie fillings, comprised of peanut butter, cream cheese, and Cool Whip. But the mousse I've had in cakes seems to be a true mousse, with what I imagine is a base of egg yolks.

I think I've finally come up with a great recipe for the mousse! You're basically making chocolate mousse - but with peanut-infused cream - and then folding in air-entrained peanut-butter frosting. The format of the assembled cake is something I've borrowed from Southern Sweets, another great Decatur-area bakery. I hope you like it!

Chocolate-Peanut Butter Mousse

  • 2 cups heavy cream
  • 1 cup chopped roasted peanuts
  • 1 (8-ounce) package cream cheese, room temperature
  • 1/2 cup (1 stick) unsalted butter, room temperature
  • 1 cup confectioner's sugar
  • 2 cups peanut butter
  • 8 ounces bittersweet chocolate, finely chopped
  • 1/3 cup sugar
  • 2 1/2 tbsp. light corn syrup
  • 5 large egg yolks
Heat the cream to a simmer. Stir in the peanuts, cover cream tightly with plastic, and return to the refrigerator, and chill several hours. Strain out the peanuts and discard.

Using a chilled whisk attachment in a chilled bowl, whip the cream to firm peaks; cover with plastic and refrigerate until firm, about 2 hours.

In the bowl of a large mixer, using the paddle attachment, beat together the cream cheese, butter, peanut butter, and confectioner's sugar until fluffy and well-blended.

Melt the chocolate, and set aside to cool slightly.

In a small saucepan, bring the sugar, corn syrup, and 1 1/2 tablespoons water to a boil over medium heat, and cook until mixture reaches 238° on a candy thermometer, about three minutes. Remove from heat.

With a whisk attachment, beat the yolks on medium-high speed until lightened, about three minutes, scraping down the side of bowl as needed. With the mixer on medium speed, gradually pour the sugar syrup down the side of the bowl in a slow, steady stream. With the mixer on high speed, beat until the mixture is thick and holds a ribbon-like trail, about three minutes more. With a rubber spatula, gently stir in the melted chocolate to combine. Fold in the peanut butter cream.

Gently fold the mixture into the whipped cream until well combined. Leave at room temperature before spreading it on the cake, up to three hours.

Chocolate cake
This is the same cake I used for the wedding cake, scaled for a single 10" pan.

  • 1 1/3 cups all-purpose flour
  • 1 1/3 cups white sugar
  • 3/4 cup unsweetened cocoa
  • 2 teaspoons baking soda
  • 1 teaspoon baking powder
  • 1/2 teaspoon salt
  • 2 eggs
  • 1 cup cold brewed coffee
  • 1 cup buttermilk
  • 1/2 cup vegetable oil
Preheat oven to 350°. Butter the bottom and sides of a 10" nonstick springform pan.

In a large bowl, combine the flour, sugar, cocoa, baking soda, baking powder and salt. Make a well in the center and pour in the eggs, coffee, buttermilk, and oil. Mix until smooth; batter will be thin. Pour into prepared pan.

Bake in preheated oven, rotating pan after 12 minutes. Check for doneness with a toothpick every six minutes or so after that; cake should take 20-25 minutes to cook.

When cake is done, remove from the oven and place on a rack to cool for 5-10 minutes. Remove sides from the springform pan. Let cake cool completely on the rack.

Chocolate Ganache
  • 4 ounces semisweet chocolate, finely chopped
  • 1/2 cup heavy cream
Place chopped chocolate in a medium bowl.

In glass bowl, microwave cream until just boiling. Pour hot cream over chocolate, and swirl to cover. Let stand 2-5 minutes, then stir until smooth.

Plus: extra chopped peanuts (about 1/2 cup), for decoration

Cake assembly

When cake is cooled completely, trim the top with a cake leveler. Eat the scraps with your Valentine.

Cut a long strip of parchment or wax paper, and wrap it around the cake, so the paper sticks up several inches. Put the sides of the springform back on, to hold the parchment in place.

Spread the mousse evenly on the top of the cake with a small offset spatula. Chill for one hour.

While it is still very liquid, pour the ganache on top of the mousse, and spread to the edges with an offset spatula. Then drop the cake a few times onto a counter-top from about 6 inches up, so that the ganache will smooth itself nicely.

Put the cake in the fridge, let the ganache set up (about 30 minutes), then unwrap the parchment paper and press chopped peanut onto the sides for decoration. Refrigerate.

Cupid will be so proud of you!


  1. Also! I scaled this mousse recipe up so that the mousse will be taller than what's shown in the pictures. And you'll have a higher mousse-to-cake ratio. Thank goodness.

  2. This looks amazing! Can I request this for my birthday next year? :)

  3. Absolutely! With cheesecake on the side.

  4. Hey, Elizabeth:

    Yes, this looks amazing, as do the rest of the pastries! I'll definitely try them. Unfortunately, Cronon's staring at me right now.:)

  5. Jessi asked me about cake flour - it's lighter and finer than all-purpose. I use Swan's Down, which is in a red box, hidden among all the cake mix boxes. If you use all-purpose instead, cut it down by a few tablespoons.