STEP ONE: Melt chocolate in a small pot with the coffee. Remove from heat and add butter, stirring to melt.

STEP TWO: Beat egg yolks and sugar. Beat in the juice, liqueur, or rum. Set mixing bowl over hot water and beat until foamy. Set bowl over cold water and beat 3-4 minutes until it cools and thickens. Beat in the chocolate mixture.

STEP THREE: Beat egg whites and salt until soft peaks form. Sprinkle on the sugar. Beat until stiff peaks form. Fold the egg whites into mousse mixture.

STEP FOUR: Divide into serving dishes or leave it one large dish–then chill at least two hours or overnight. Top with whipped cream or a creme anglaise sauce.