Chocolate Mousse

Directions

1. 1
   Whisk egg yolks, 1/4 cup sugar, unsalted butter and 1/4 cup water in large metal bowl to blend.
2. 2
   Set bowl over saucepan of simmering water; whisk constantly until thermometer inserted into mixture registers 160F, about 3 minutes.
3. 3
   Add chocolate and whisk until melted and smooth.
4. 4
   Turn off heat; leave bowl over water.
5. 5
   Beat egg whites in another large bowl until soft peaks form.
6. 6
   Gradually add remaining 1/4 cup sugar and beat until stiff but not dry.
7. 7
   Fold 1/3 of beaten whites into chocolate mixture to lighten.
8. 8
   Fold in remaining whites.
9. 9
   Divide mousse among 6 small dessert glasses.
10. 10
    Chill until set, at least 3 hours or overnight.