From: Art of Gluten-Free Baking (http://artofglutenfreebaking.com)
-adapted from Bouchon Bakery, by Thomas Keller and Sebastien Rouxel
For the cake
For the filling
For the coating
Preheat oven to 350 degrees F/180 degrees C/Gas Mark 4. Line the bottom of a rimmed half-sheet pan (18 in x 13 in/46 cm x 33 cm) with parchment paper.
Sift together the flour and the unsweetened cocoa into a small bowl. Whisk to combine.
Place the 2 whole eggs, the 2 egg yolks, and the 1/2 cup of sugar into the bowl of a stand mixer fitted with the whisk attachment. Mix on low speed for a few seconds to combine. Raise speed to medium high and beat for 10 minutes. By the end of the 10 minutes, the mixture should be light in color and about 3 times its original size.
Place the 2 egg whites into the clean bowl of a stand mixer fitted with the whisk attachment. Beat for about 1 minute–until foamy. Sprinkle the 2 tablespoons of sugar over the top and beat on medium high for 2 minutes, until the whites are glossy with soft peaks.
Fold the flour mixture into the egg yolk mixture in 2 additions. Do this by sprinkling half of the flour mixture over the egg yolk mixture and folding it in. Sprinkle with the remaining flour and carefully fold it in. Make sure that all of the flour mixture is combined with the egg mixture. You will find hidden pockets of it in the middle of the egg mixture as you do the folding–so make sure it’s all incorportated. Then fold in the egg white mixture in 2 additions.
Spoon out mixture onto the prepared pan. Tip: put equal amounts of the mixture onto each of the four corners of the pan and on the middle of the pan. Carefully spread the batter into an even layer across the pan–using your fingers here and there to stabilize the parchment paper. Smooth the top as best as you can. I use an offset spatula to do this. Be sure the mixture reaches the corners of the pan.
Bake at 350 degrees F for 15 minutes–until a tester inserted into the middle of the cake comes out clean. Do not overbake. Set the cake, in the pan, on a cooling rack to cool completely (at least an hour).
15 minutes before you want to use it, make your filling. In the clean bowl of a stand mixer fitted with the whisk attachment, place the cream. Sift the powdered sugar across the top. Add the vanilla extract along the side of the cream. Beat on medium high until the cream holds its shape when you lift out the whisk. You don’t need it to be overly firm–just firm enough that you can spread it across the cake without it being liquid and runny.
Once the cake is cool, cut it. First, run a sharp knife around the edges of the cake to separate it from the pan. With the long side of the pan facing you, measure and mark with a sharp knife three equal 5.5 in/14 cm sections of the cake from left to right. Cut from top to bottom along the marks. You should now have three rectangular sections of cake cut, each about 5.5 in x 10 in/14 cm x 25 cm.
Next, tightly wrap each section separately in a large piece of plastic wrap. Lay down the plastic wrap the counter and place the rolled cake log at one end. Then roll up the first section of cake into the plastic and fold the plastic over the ends. Repeat for the other two cake logs. Place each rolled section into a large ziploc bag and place each in the freezer for at least 1 hour. You will cut and enrobe the cakes in chocolate after they are frozen.
At this point you can leave the rolled cakes in the freezer for up to 5 days.
Enrobing the cakes with the chocolate:
Cover a large cookie sheet with waxed paper. This is where you will place your chocolate enrobed cakes to solidify.
Remove your cake logs from the freezer, unwrap (but keep the plastic wrap), and cut each log into 4 equal pieces, each about 2 inches long. Keep the pieces in the log form and rewrap and place back in ziploc bag and return the bags to the freezer.
Place your semisweet chocolate in a heat proof bowl on top of a pot full of simmering (not boiling) water. Have ready another small, deep bowl that is just big enough for the 2 inch cakes to be rolled in.
Watch carefully as the chocolate melts, using a whisk to stir it. Once the chocolate is just barely melted, turn off the heat on the simmer water. You will now need to move quickly.
Spoon out about 1/3 of the melted chocolate into the smaller bowl, taking care not to get any water drips into the chocolate. Remove the first log from the freezer and unwrap. With your fingers, take hold of the first 2 inch section by the open ends. Place the log into the small bowl of chocolate and carefully roll one half. While still holding the section by the ends, use a butter knife or an offset spatula to spread some of the chocolate that is already on the cake to cover the remainder of the cake, leaving the ends uncoated (it’s too hard to get the ends coated). Note: it’s a messy process. Place the enrobed section on the pan lined with the plastic wrap and repeat the process with the remaining sections in that log.
The chocolate in the small bowl will now have some little bits of cake and cream in it. If this bothers you, scrape out the bowl before you add the next 1/3 of melted chocolate. I don’t bother doing this. I just spoon another 3rd of the chocolate into the small bowl and proceed to the next log sections. Repeat the dipping, rolling, and smoothing process with the remaining 2 cut logs. Be sure to place the remaining 1/3 of chocolate in the small bowl before you dip the last log sections.
Your waxed paper lined baking sheet will now contain 12 chocolate covered cakes. Let them sit at room temperature until the chocolate is fully set. At this point you can eat them. For storage, I place the cake lined baking sheet into the refrigerator to cool down the cakes. Once they are fully cool again (about an hour), I carefully place them into into a ziploc bag to store in the fridge.
Serve cold or at room temperature.
Store the Ho Hos in the fridge for up to 3 days or in the freezer for up to 2 months. To defrost, place in the fridge for 24 hours.