2 tablespoons plus 2 teaspoons unsweetened cocoa powder
8 tablespoons unsalted butter
1/2 cup heavy cream
2/3 cup confectioners' sugar, sifted
2 large egg whites
4 large egg yolks
6 ounces bittersweet chocolate (about 72%)
1 tablespoon granulated sugar
1 tablespoon confectioners' sugar
1/2 cup heavy cream
1. Lightly oil a 11/2-quart terrine or a loaf pan. Line smoothly with plastic wrap, allowing a 2-inch overhang on the long sides.
2. Sift together 2/3 cup of the confectioners' sugar and the cocoa. In the top of a double boiler (or in a heat-proof bowl set over a pot of barely simmering water), melt the chocolate and butter, stirring together until smooth. Remove the bowl from the heat and let cool slightly. Whisk in 1 yolk at a time, then whisk in the cocoa powder mixture until smooth. Remove from the heat.
3. In a stand mixer fitted with the whisk attachment, whip 1/2 cup of the cream on high speed until it forms soft peaks. When the whisk attachment is removed it should leave behind soft spikes in the cream.
4. Thoroughly wash and dry the mixer bowl and whisk, then return them to the stand mixer. Whip the egg whites and the granulated sugar on high speed until the meringue forms medium peaks, about 2 minutes. When the whisk attachment is removed, it should leave behind distinct but not stiff spikes in the meringue.
5. Using a rubber spatula fold the meringue into the chocolate. Gently fold in the whipped cream until the batter is evenly blended. Pour into the prepared mold, cover with the overhanging plastic wrap, and refrigerate until firm, at least overnight or up to 5 days.
6. To serve, whip the remaining 1/2 cup whipped cream with the remaining 1 tablespoon confectioners' sugar until it forms soft peaks.
7. To serve, remove the overhanging plastic wrap and invert the terrine onto a cutting board. Fill a pitcher with hot water and place a sharp knife in the water to warm the blade. Peel away the plastic wrap. Dry the knife on a clean kitchen towel, then slice the terrine crosswise into 1/2-inch pieces, periodically dipping the knife back into the water to clean the blade and rewarm it. Place each slice on a chilled plate and garnish with a spoonful of jam and dollop of whipped cream.