Italian Buttercream

Place water, sugar and glucose in a heavy sugar pan. Stir until mixture boils, wash down sides with wet, clean pastry brush and insert candy thermometer. Boil until the temperature of the syrup reaches 110°C or 230°F, then start beating the egg whites in a stand up electric mixer, until stiff. When sugar reaches 120°C or 248°F remove from heat and put the speed of the egg whites to the lowest. Pour the syrup into the whipped whites in a slow, steady stream, trying not to get syrup on the wire whip or the edge of the bowl. Continue to beat the meringue until it is nearly cold, about 15 minutes at low or medium-low speed, depending on your machine. Begin beating in the butter, a little at a time, and continue beating until smooth. If making ahead, let buttercream come to room temperature for about an hour before mixing.

Notes:
Good basic recipe. Adapted from:
Roux, Michel and Albert. The Roux Brothers on Patisserie: Pastries
and Desserts from 3-Star Master Chefs. New York: Prentice, 1986.