Bouchon Bakery’s pastry chef, Alessandra Altieri, shares her interesting twist on a classic dessert: chocolate mousse.
(It should be noted that all measurements are by weight, so any measurements in ounces are weights, not fluid ounces.)
*Note: Having trouble filling the pastry bag? It helps to think of it as an ice cream cone. Take the broad opening with both hands and fold the ends downward to form a large lip. Grasp the pastry bag in one hand, holding it just underneath the lip you just formed. With a rubber spatula in your other hand, scoop the mixture into the pastry bag, filling it about halfway up. Unfurl the lip, and twist.
Melt both the milk chocolate and dark chocolate over a double boiler: Place the chocolate into a glass or nonreactive bowl. Fill a saucepot with just enough water to barely touch the bottom of the bowl when it is placed on top. Set over medium heat, and bring the water just to a simmer. After the chocolate has melted completely, allow to cool to about 100 degrees. Maintain the chocolate at this temperature (keep a thermometer handy); you may need to cover the bowl or light the stove again to maintain this temperature.
Next, soak the gelatin in cold water for about 5-10 minutes, or until soft. Meanwhile, add about 2 pounds of the heavy cream to a bowl, and set over another bowl filled with ice water. Beat with an electric mixer on medium speed until soft peaks form. Set aside.
Now, take the remaining cream and combine with the milk in a saucepan. Place over medium heat, and bring to a boil. Immediately remove from heat. Allow the mixture to cool for at least 1 minute.
Combine the egg yolks and sugar in a bowl, and whisk until the mixture is pale yellow. Temper the mixture by pouring about 1/3 of the milk-cream mixture into the bowl, continuing to whisk. Then, pour the mixture back into the saucepan and place over low heat. Cook, stirring constantly with a wooden spoon, making contact with the bottom of the pan, until the custard coats the back of the spoon, and a finger drawn through it leaves a clean line that does not run.
Do not walk away from the custard: It will look like nothing is happening for a long time, but when it starts to set, it will happen very quickly, and you may end up with scrambled eggs in a matter of seconds. While stirring, make sure to pay attention to the edges of the pan, as the eggs tend to coagulate there.
When the custard is done, remove immediately from heat. Squeeze the gelatin dry, and incorporate into the custard. Pass through a fine mesh strainer into the bowl with the chocolate. Whisk to combine thoroughly. Next, fold in the whipped cream 1/3 at a time, making sure that each batch is fully incorporated before adding more.
Take a pastry bag and fill it with the mixture about halfway up.* Twist, and apply a gentle pressure at the top to move the mixture downward all the way towards the point. Cut off a small hole at the point. Pipe the mixture into a silicone mold with dome-shaped spaces, and smooth the tops over with an offset spatula. Place in the freezer until frozen solid. When ready to serve, remove from freezer and carefully pop out the domes from the mold.