1 tbsp. butter
3 (1 oz.) squares unsweetened chocolate
2 eggs, divided
1/2 c. sugar, divided
2 tbsp. dark rum
1 tsp. cold strong coffee
1 c. heavy cream, whipped

In small heavy saucepan over low heat, melt butter and chocolate. Stir until smooth; set aside. In small bowl, beat egg whites until foamy. Gradually beat in 1/4 cup sugar until stiff peaks form; set aside.

In large bowl, beat egg yolks with 1/4 cup sugar until lemon colored and light. Beat in rum and coffee. With rubber spatula fold in chocolate mixture and whipped cream just to blend. Spoon into 4 individual serving dishes. (If desired can reserve 1 cup mousse and put in pastry bag with fluted tip and form rosettes on servings.) Chill overnight or several hours.