Black pepper is the unexpected, but oh-so right touch, that magnifies the deepest, darkest depths of really good chocolate in this Frozen Chocolate Mousse Cake.
- 3/4 cup finely ground almonds (almond flour)
- 4 tablespoon cocoa powder
- 4 tablespoon all-purpose flour
- ¼ teaspoon kosher salt
- 2 large whole eggs
- 1 cup granulated sugar (divided)
- ⅓ cup vegetable oil (plus more for greasing pan)
- ½ cup sour cream
- 15 ounce dark chocolate (70% cocoa)
- 2 teaspoon very finely ground black pepper (use a mortar and pestle)
- 6 egg yolks
- 6 egg whites
- coarsely ground black pepper (to taste)
Make the cake base: Place the oven rack in the center position, then preheat the oven to 350 degrees F.
Grease the bottom and sides of an 8x8-inch square cake pan. Line the bottom with a piece of parchment sized to fit, then grease the parchment; set aside.
In a medium bowl whisk together, ground almonds, cocoa powder, flour and salt; set aside.
In a large bowl whisk 2 whole eggs, ½ cup sugar, ⅓ cup oil and sour cream until well-combined. Working in three additions add the dry ingredients to the wet ingredients, mixing them until just combined between each addition. Do not over mix the batter.
Scrape and smooth the batter into the prepared cake and bake in the heated oven until a toothpick inserted in the center comes out clean, about 20 minutes.
Let the cake cool to room temperature in the pan on a rack, then carefully turn the cake out onto a flat surface; peel off and and discard the parchment.
Wash and dry the same cake pan you baked the cake in, then line the cake pan with 2 sheets of plastic wrap overhanging all 4 sides by at least an inch. Try and line the pans neatly, too many wrinkles will make the cake difficult to unwrap later. Place the cake base back into the plastic-lined cake pan; set aside.
Make the mousse: Chop the chocolate into coarse chunks, then place it in a large heatproof bowl. Set bowl over a pan of simmering water to melt the chocolate, stirring occasionally, until very smooth. Remove from heat and stir in the very finely ground black pepper. Allow the chocolate pepper mixture to cool slightly, then beat in 6 egg yolks one at a time; set aside.
Place 6 egg whites in a medium mixing bowl, using a balloon whisk or an electric beater fitted with a whisk attachment, whisk to soft peaks. Add remaining ½ cup sugar and continue to whisk until the mixture is stiff and glossy, but not yet dry.
Fold a big spoonful or two of the whites into the chocolate mixture to lighten, then carefully and lightly fold in the rest of the meringue. Spoon the mixture onto the prepared cake base, then use an offset spatula to smooth the top. Sprinkle with coarsely cracked black pepper, not too much just enough to be attractive.
Cover the mousse-topped cake with plastic wrap, do not let the plastic wrap touch the surface. Transfer the cake to the freezer to freeze completely, at least 4 hours and up to 3 days.
To serve: Remove the top piece of plastic wrap from the frozen cake. Use the overhanging plastic wrap to gently pull the cake from the pan all in one piece. Remove the plastic wrap from the cake and discard. Use a serrated knife to trim the four sides of the cake for a neater appearance (optional), then cut the cake into 8 equally-sized pieces.
Let the cake sit 10 to 20 minutes to thaw just a little, then serve immediately.