The Birthday Cake
Jul. 13, 2009 5:58 pm
Updated: Jul. 16, 2009 9:34 am
My husband P. and a close friend F. share a birthday. This year, it was their fortieth—and our friend, who is a caterer, was planning a blow-out bash. Since F. was making incredible food, it was up to me to make an incredible cake—and a big one, for up to 70 people. The flavor request? A chocolate-peanut butter cake, but with no buttercream, at F.'s request. "I like buttercream…but after a couple of bites, you feel like you're just eating a big ol' stick of butter."
Here's what I made: a chocolate sour cream cake for the base layers, a peanut butter Bavarian cream, a milk chocolate soft ganache, a peanut butter cup filling, and a semisweet chocolate ganache for the glaze. To serve that big of a crowd, I made a half sheet-pan-sized cake. I didn't want the cake to be too rich or cloyingly sweet, so I chose a Bavarian cream layer to give it most of the peanut butter flavor. I was also somewhat hamstrung by the "no buttercream" rule: I needed something to spread on top of the cake that would firm up and make a beautiful smooth surface for the ganache. Normally, I would use buttercream as a crumb coat; it allows you to make sharp edges and flat surfaces on the cake so the glaze doesn't show lumps or pick up crumbs. I dug around in my culinary school notes, and found Chef Budd's peanut butter cup filling recipe. I decided to double the recipe and use one layer on top of the Bavarian cream, for a salty burst of peanut butter flavor, and one layer on top of the cake, for a smooth surface. It worked perfectly.
I made two batches of chocolate sour cream cake from a recipe I like in The Wedding Cake Book by Dede Wilson. That gave me three half sheet pans of cake (plus a pan of cupcakes made with the extra batter). I also made a batch of crème Anglaise for the Bavarian cream, and made the milk chocolate ganache. Soft ganache—made with two parts cream to one part chocolate—can be whipped into a filling or frosting, but you have to refrigerate the mixture overnight. This allows the cream to form an emulsion again (chilling redistributes the fat globules in the cream) so that you can whip it like whipped cream. I also made a vanilla simple syrup. After the cake layers cooled, I topped them with a sheet of parchment and wrapped them completely in their sheet pans in plastic wrap and left them on the counter overnight.
I made a milk chocolate ganache because I think the less assertive flavors work better with peanut butter. I really like this recipe used as a chocolate whipped cream.
Milk Chocolate Soft Ganache
15 oz. milk chocolate
18 oz. heavy cream
6 oz. whole milk
1.5 oz. unsalted butter
Chop the chocolate and place it in a bowl. Scald the milk and cream; stir in the butter. Pour the hot cream over the chocolate. Cover the bowl for about five minutes to soften the chocolate. Whisk the mixture or use a buerre mixer (stick blender) until smooth and homogenous. Refrigerate overnight before using.
16 oz. whole milk
16 oz. heavy cream
1 tsp. salt
8 oz. sugar
10 oz. egg yolks
1 Tbsp. vanilla extract
Combine the milk and cream, salt, and half the sugar. Bring to a boil. Blend the yolks and the rest of the sugar (don't do this too soon, or you'll "burn" the yolks—the yolks form hard little pellets that don't incorporate with the custard). Temper in the hot milk: slowly pour the hot milk mixture into the yolks, whisking constantly. Return the mixture to the saucepan. Cook over medium heat, stirring constantly with a wooden spoon, until the custard coats the back of the spoon: you should be able to draw a clear line down the back of the spoon with your finger. Remove from heat and immediately strain the mixture through a fine mesh sieve. Cool the mixture quickly over an ice water bath and refrigerate.
I measured out 24 ounces of crème Anglaise and added the hot custard to 8 oz. of creamy peanut butter to make the flavor base for my Bavarian cream. I saved the rest of the custard and served some of it with berries and angel food cake (delicious!) and used the rest instead of milk to make French toast (outstanding!).
For a cake form (a mold in which to build the cake and let the layers firm up), I used a roasting pan lined with foil. I left enough of an overhang so that I could use the ends of the foil to lift the finished cake out of the mold. (A fine plan…except that I hadn't counted on the weight of my massive cake. I should've added a layer of plastic wrap for easier maneuvering, since the foil ripped when I tried to lift the cake.)
A real Bavarian cream is made from a crème Anglaise base combined with whatever flavor puree you want to add (sweetened fruit purees, chocolate, nut pastes) and then lightened with whipped cream and stabilized with gelatin. Unlike gloopy doughnut fillings, Bavarian creams should be very light and delicate, not rubbery. Since you have a limited window of opportunity to spread the filling before the gelatin starts to set, you need to have everything ready to go before you mix it. I placed my first cake layer—resting on a cake board—in the bottom of the prepared pan, and used extra strips of cardboard wrapped in foil to create straight sides in the mold, since the roasting pan had sloping sides. I greased the edges of the foil that would be in contact with the Bavarian cream with a very light coating of cooking spray. I soaked my cake layer with simple syrup.
Peanut Butter Bavarian Cream
1 oz. gelatin
8 oz. cold water
32 oz. heavy cream
32 oz. peanut butter vanilla sauce (24 oz. crème Anglaise mixed with 8 oz. peanut butter)
Bloom the gelatin in the cold water for about ten minutes. Meanwhile, whip the cream to soft peaks; refrigerate.
Melt the gelatin over a double boiler while you warm the vanilla sauce slightly (adding gelatin to a cold solution will cause it to gel suddenly and form rubbery little pellets. No good). Blend the gelatin into the warm vanilla sauce. Strain and cool slightly. Fold 1/3 of the sauce into the whipped cream until well combined; fold in the remaining 2/3. Immediately pour the cream into prepared molds or dessert glasses.
I put the cake with the Bavarian cream layer in the fridge to set, and made the peanut butter filling.
Peanut Butter Cup Filling
10 oz. peanut butter
4 oz. milk chocolate
1 oz. cocoa butter
Chop the milk chocolate. Melt the chocolate and cocoa butter separately. Mix all of the ingredients to combine; cool to room temperature.
When the Bavarian cream was set and the peanut butter cup filling was cool, I spread a thin layer of filling on top of the Bavarian cream and added my second cake layer. I brushed it with simple syrup, and then whipped the chocolate ganache. I spread on the chocolate ganache filling, and then added my top cake layer. I spread the rest of the peanut butter cup filling onto the top of the cake and returned the cake to the fridge to firm up.
Finally, the end was in sight! I only had one more component to make: the semisweet ganache glaze. I used 3# of semisweet chocolate chips and 24 oz. of cream—I probably could've used more cream, because the ganache was very thick.
To make the ganache, I scalded the cream and added it to the bowl of chocolate chips. Just as with the soft ganache, I covered the bowl with a big pot lid and let the chocolate soften for about five minutes in the hot cream before whisking.
To glaze the cake, I removed it from the mold. I set it on a cooling rack over two sheet pans to catch the drips. The peanut butter layer on the surface of the cake cracked when I unmolded it, but I used a hot knife to melt and smooth the peanut butter layer, and used a small offset palette knife to add some of the ganache to an uneven corner to build it up a little and smooth it out. I poured the ganache over the cake, using a medium offset palette knife to smooth it over the cake's surface. I poured some over the sides, working quickly to get the cake covered. I let the ganache cool and harden, and then used extra ganache in a parchment paper cone for the decorative piping. The extra ganache (scraped from the clean sheetpan into a plastic container) makes a delicious hot fudge sauce for ice cream.
The cake was devoured—it was creamy, salty, sweet-but-not-too-sweet…the birthday boy declared it "exactly what I wanted!" I did myself proud.
Chocolate Cake with Peanut Butter Filling
Chef Budd's Peanut Butter Cup Filling: peanut butter, milk chocolate, and cocoa butter
Peanut Butter Bavarian Cream Layer in makeshift cake mold
Semisweet chocolate ganache
Unmolded cake: a cross-section of cake layers, Bavarian cream, whipped ganache & peanut butter layer
Cracks in the unmolded cake! Don't worry, it's fixable.
Closeup of layers