8 oz. best-quality white chocolate, broken into small pieces
1/2 c. (1 stick) unsalted butter
6 eggs, separated, room temperature
1 c. sifted confectioners' sugar
1/2 c. Frangelico liqueur
2 c. whipping cream, cold
Pinch of cream of tartar
Unsweetened cocoa powder or grated dark chocolate (garnish)

Melt the white chocolate and butter in a small saucepan, stirring constantly. Set aside.

Beat the egg yolks, sugar and liqueur until the mixture forms a slowly dissolving ribbon when the beaters are lifted. Pour the mixture into the top of a double boiler and cook, whisking constantly, over simmering water until very thick, about 3 minutes.

Remove to a large mixing bowl. Whisk in the white chocolate mixture and stir until smooth and cool.

Beat the cream until the peaks are stiff. In a separate bowl with clean beaters, beat the egg whites with the cream of tartar until stiff but not dry. Gently fold into egg whites into the chocolate mixture, then fold in the whipped cream. Refrigerate covered until set, about 3 hours.

Spoon the chilled mousse into individual ramekins or goblets. Sprinkle with cocoa or grated chocolate. Makes 8 to 10 portions.