Chocolate Mousse

Melt chocolate and butter in a bowl set in a pan of simmering water. When the chocolate has melted, remove from the heat. In another bowl set in simmering pan of water, whisk together egg yolks, sugar, and vanilla extract. Whisk constantly until mixture is thick like whipped cream (it’s thick enough when you can see the bottom of the bowl as you whisk it). Remove the bowl from the heat. Using a plastic spatula, fold in the warm chocolate and let cool about 5 minutes. In a chilled mixing bowl with chilled beaters, whip the cream on high speed until it holds soft peaks. Gently fold the whipped cream into the chocolate mixture (it doesn’t have to be perfectly combined.) Place the egg whites in a chilled mixing bowl and whip on high speed until they hold soft peaks. Gently fold the whites into the chocolate mixture, mixing just until the mousse is smooth. Divide the mixture into serving dishes or wineglasses and refrigerate until chilled, about 2 hours.