Step 1Place yolks in top of double boiler set over, but not touching, simmering water. Cook slowly while beating steadily with eggbeater or hand mixer until pale yellow and slightly thickened. Add sugar and beat thoroughly until sugar dissolves, about 6 to 8 minutes. Pour in Sherry and stir thoroughly with spoon until custard becomes thick, 5 to 6 minutes. Remove from heat. Place custard in bowl and allow to cool.
Step 2To serve, beat cream until stiff. Fold into custard and blend completely. Add raspberries, turning them carefully with spoon until completely covered by custard-cream. Place rasberries and cream in 6 dessert glasses and refrigerate 30 minutes. Before serving, dip reserved raspberries into powdered sugar and place on top of each dessert glass. Serve cold.