Servings: About 2 cups, enough for 1 (4 x 11-inch) four-layer-cake or 1 dozen cupcakes

1 1/4 cups granulated sugar 1 ¼ cups granulated sugar
1/4 cup water ¼ cup water
6 egg whites 6 egg whites
1 cup butter, room temperature, cut into 1-inch cubes 1 cup butter, room temperature, cut into 1-inch cubes

In a medium pot, place 1 cup of the sugar and the water. Give the sugar a stir with a spatula and then clip your candy thermometer to the side of the pot. Bring to a boil over high heat without stirring. Turn down the temperature slightly to maintain a low boil until the candy thermometer reads 240°F.
In a stand mixer fitted with a whisk attachment, beat the egg whites on medium speed until soft peaks form. Slowly add the remaining ¼ cup sugar and then turn the mixer speed to high and whip until stiff peaks form.
Remove the pot of hot syrup from the heat. With the mixer running on low speed, slowly add the hot syrup to the egg whites. Try to avoid hitting the beaters with the syrup with adding it as it will splatter and could  cause lumps.
Continue beating on medium speed until the egg whites are cool. You can then start to add the butter one piece at a time until it is all incorporated. The egg whites may appear to deflate once you add the butter, but don't panic. Continue beating until the butter starts to get fluffy and you will have a lovely silky Italian butter cream.

Gingerbread Italian buttercream: 2 tablespoons fancy molasses, 2 teaspoons pumpkin pie spice  Gingerbread Italian buttercream: 2 tablespoons fancy molasses, 2 teaspoons pumpkin pie spice
Coffee Italian buttercream: 2 tablespoons espresso powder combined with 1 tablespoon hot water to create a coffee paste  Coffee Italian buttercream: 2 tablespoons espresso powder combined with 1 tablespoon hot water to create a coffee paste
Chocolate Italian buttercream: 1 teaspoon pure vanilla, 1/2 cup dark chocolate chips, melted and cooled  Chocolate Italian buttercream: 1 teaspoon pure vanilla, ½ cup dark chocolate chips, melted and cooled