Chocolate Mocha Inside-Out Cake

More years ago than I care to admit, there was a show on public television called Cooking at the Academy. On one episode, the chef made a cake that made my jaw drop. It was two different flavors of cake layered with mocha and chocolate buttercream, but the surprise came when they cut a slice. I HAD to make that cake!

Back in the early 90's, I baked but still had a lot to learn, only I didn't realize it. Ah, youth. I made the cake for a co-worker's bridal shower and it was a huge hit. It's a bit labor-intensive so I've only made it a handful of times but it always commands the attention of my guests, and devout bakers are struck by the inside cross section and are similarly driven to make it themselves. If you make it, and I hope you will because it's delicious, here are a few things to keep in mind:

• Give yourself a good solid day to make the cake. There are lots of steps that require letting the cake chill or the buttercream soften, not to mention the quality time you'll be spending with your mixer. If you need it for a special event, you can make it the day before and refrigerate it overnight. Just let it come to room temperature for about 20 minutes before serving (depending on the season and temperature in your house).
• Before you start making the cake, fill your sink with hot, sudsy water. This will make the clean up much easier. When you finish with a bowl, beater, or measuring cup, just set it in the sink.
• Almond paste that's old can be rock-like and that's hard to blend in with the cake batter. I've never done this but if you want the best results, I suggest you investigate making your own almond paste. Failing that, beat the almond paste-egg white mixture in your stand mixer fitted with a beater blade (the paddle with the spatula-like scraper) until smooth. I find it very difficult to do this by hand, and every time I make the cake, I end up with chunks of almond paste that I don't see until the layers are baked.
• When the recipe calls for dividing the batter between the cake pans, I weigh the batter using my spare mixing bowl to tare (set to zero) the scale, then I weigh the bowl that has the cake batter in it. I divide the weight in half and write it down. Then I place one of the prepared cake pans on the scale, tare it, then measure a little less than half of the batter into the pan as directed. I'm not good at eyeballing batters and this method keeps me out of trouble.
• I don't have an espresso maker, so I ask the barista at my neighborhood coffee shop how many ounces are in a shot, then I order that many shots. I get the shots for the buttercream in one cup and the shots for the brushing liquid in the other. Wasteful I know but the clean up from making this cake is daunting, kinda like running a marathon and then walking two hours to get home.
• No matter how tempted you are, don't substitute butter for the margarine. I have tried on at least three occasions and my mocha buttercream broke all three times. Only when I made a note in the cookbook did I stop making this mistake.
• If you don't have 10" cake pans, buy some. Seriously, this is the cake of a lifetime and it's worth the investment. If that just isn't in your budget with the other supplies you'll need, use your 9" pans. Any smaller and I'm afraid your crater will be wonky and the cake won't look right when you slice it.
• The cookbook says to put the rest of your mocha buttercream in a piping bag fitted with a #4 plain tip and pipe the buttercream in a circular fashion on top of the cake, starting in the middle and working your way to the edge. It looked lovely when he did it, but he's a professional chef-instructor and I'm a piping failure. I've never done it for two reasons: One, I've never had enough extra mocha buttercream and two, the cake has enough buttercream already. Any more and it would just be too rich for most people.
• To reinforce this point, more is not better with this cake. You want to brush on the espresso mixture sparingly, enough dampen the layer to get the flavor but you definitely don't want to make the cake wet. Same with the buttercream: more is not better. More is too much. Besides, it's SO much better to take that last layer and your extra buttercream and a biscuit cutter or sharp knife and make your own cake creation with it. Consider that dinner the night you're making the cake. If a friend helps, you can eat your plated desserts you make with the scraps and get very excited about cutting the cake later. It also helps to fuel up before the clean up.
• I like to be nonchalant when I cut this cake so I try not to build up people's expectations. I mean, it would be awful to get them all riled up and then I cut it and it looks like a cubist Picasso painting inside. The first time especially, let them be surprised. Their surprise is better than the enjoyment you'll get from trying to explain it, plus it's almost impossible to explain without pictures.
• I recorded the show on VHS when it was on, but I seriously worry about the quality and longevity of VHS tapes. Amazon has the episode on VHS, and I think I'm going to buy it and then have it converted to a DVD. I wish I had a video clip of the part where you cut out the cone and make the crater because it does help to see how it is done.

Chocolate Mocha Inside-Out Cake - adapted from Cooking at the Academy
Printer-friendly recipe
Sponge cakes
2 egg whites
10 ounces almond paste
12 large eggs, separated
1 1/3 cups/10 ounces granulated sugar
1 teaspoon vanilla extract
2 3/4 cups/8 ounces cake flour, sifted
2/3 cup/1 ounce natural (not Dutch process) cocoa powder

Buttercreams
1 pound unsalted butter, softened
5 ounces margarine, softened (don't substitute butter)
1 cup egg whites (from 7 or 8 eggs)
1 pound sugar
1 teaspoon vanilla extract
6 ounces melted dark chocolate
1/2 cup brewed espresso (not instant), cooled

For Assembly
1/4 cup brewed espresso, cooled
1/3 cup water
1/2 cup toasted sliced almonds
Dark chocolate shavings

Other
2 10" cake pans
Parchment paper rounds
Cardboard cake rounds

Prepare the spongecakes:
Mash the almond paste with the back of a spoon to break it apart and get out the lumps (see note above). Mix in the two egg whites and set aside.

Preheat oven to 375 degrees. Line two 10" cake pans with parchment rounds and set aside.

Place the egg yolks in a mixing bowl on stand mixer and add 1/2 cup of the sugar. Beat with the paddle attachment on medium-high speed until the egg yolks are pale yellow and the mixture falls in a ribbon if the beater is lifted, at least 5 and preferably 10 minutes. Add the vanilla.

Gently stir the yolks into the almond paste with a spatula and set aside.

In another mixing bowl, whip the egg whites on medium-high with the whisk attachment until they foam, then slowly add the rest of the sugar. Beat just until the egg whites form stiff peaks. Carefully fold the egg whites into the almond paste mixture. Gently fold in the flour with a spatula, being careful not to deflate the egg whites.

Pour a little less than half of the mixture in one of the prepared cake pans, smooth the top and set aside.

Sift the cocoa powder into the remaining batter and fold in to combine - don't overmix! Put the remaining batter in the second cake pan and smooth the top. Place both layers in the preheated oven and bake 23-25 minutes, until tops spring bake when touched. Remove layers from oven and cool completely on a rack.

When cool, run a thin, sharp knife around the edge of each cake layer and invert onto a rack. Peel off parchment paper and invert again (so top of layer is up).

Prepare the buttercream:
Beat together the the butter and margarine in a small bowl and set aside.

Combine the egg whites and sugar in a mixing bowl and place the bowl over a pan of simmering water and whisk constantly for about 3 minutes or until the sugar is dissolved. Be careful not to cook the egg whites!

Remove the bowl from the pan and place it on a stand mixer fitter with the whisk attachment and whip until the mixture has cooled considerably and has formed stiff peaks. Lower the speed of the mixer and add the vanilla extract. With the mixer still on low, gradually add the butter mixture and whip until combined.

Divide the buttercream (you'll have about 6 cups total) into two bowls. Add the melted chocolate to one bowl and stir with a spatula to combine, and add the 1/2 cup expresso to the other bowl, similarly using a spatula to combine. Set both bowls aside.

To assemble the cake (the fun part):
Cut the almond sponge into three even layers. Reserve the top layer for another use (you'll only need two almond layers). Cut the chocolate sponge into three even layers.

Combine the 1/4 cup espresso and water in a small bowl. Place one of the chocolate layers, cut side up, on a cardboard cake round. Using a pastry brush, lightly moisten the layer with the expresso mixture. Spread a layer of mocha-flavored buttercream and shave it down to about 1/4" thick, bringing it to the edge of the layer.

Place an almond layer on top of the mocha buttercream. Moisten the almond layer with the espresso mixture, then spread a layer of the mocha buttercream and shave it down to about 1/4" thick, bringing it to the edge of the layer.

Repeat with another chocolate layer, brushing the chocolate layer with the espresso mixture and adding the buttercream and then ending with an almond layer on top. Don't brush the almond layer or top it with buttercream. You will have one chocolate layer left. Chill the cake for 15 minutes to set the buttercream.

To cut the cake, dip a sharp, thin knife (I find a boning knife works better than the serrated knife that the recipe calls for) in hot water and wipe dry. Holding the knife at approximately a 30 degree angle approximately 3/4" in from the edge of the cake, carefully and gently cut a cone-shaped section from the center of the cake, about 8" wide at the top and and 2" wide at the bottom (or "tip"). Think of it as the crater of a volcano. Wipe your knife clean. Place your hand flat on the top of the cone-shaped wedge and using the knife or an icing spatula, remove the wedge and invert it onto your hand. Place the cone-shaped wedge, flat side down, on a cardboard cake round or a plate lined with parchment paper and set it aside.

It's kind of wonky but here's the cone for this one

Working inside the "crater," spread a layer of chocolate buttercream, about 1/4" thick, lining the inside of the crater.

Place the reserved chocolate sponge layer on top of the cake (almost like putting a roof on top of the crater).

Place a cardboard cake round on top and invert the cake so the new chocolate layer is now on the bottom and the first almond layer is on the top.

Cover the cake and set it aside (not in the refrigerator) to let the buttercream soften in between the layers.

Now, reconstruct the crater. To do this, gently press on the center of the top of the cake, gently pushing the inverted crater down to meet the bottom layer. In this new crater, spread a layer of chocolate buttercream all the way around and to the edge, making sure the buttercream is about 1/4" thick. The crater won't seem as deep or as sharp around the edges, and that's OK.

Still wonky, but the buttercream will help hide the flaws

Invert the cone-shaped wedge and set it, pointy side down, flat side up, in the crater, and gently press it into place (if needed). Using a chef's knife, trim the sides of the cake to the original shape (in the event reconstructing the cake has made bits stick out, you can trim it a little to make it round again).

Spread the remaining chocolate buttercream on the top and sides of the cake. Press the toasted almonds around the side of the cake. Top the cake with dark chocolate shavings if desired.

Serve immediately, or refrigerate until needed. Set out at room temperature 20-30 minutes before serving.