chocolate buttercream frosting recipe

I am looking for a good chocolate buttercream frosting recipe.

I refer to this one as the "When You Just Don't Give a S**t About Your Arteries Anymore Chocolate Frosting." Makes enough to frost a two layer 9" round cake.

8 ounces good bittersweet chocolate, finely chopped
1 cup sugar
1 cup room temp egg whites (about 7 to 8 large eggs)
4 sticks (1 lb) unsalted, room temp butter
1 teaspoon hazelnut extract (optional)

Melt chocolate in the top of a double boiler over medium heat until smooth. Remove from heat and cool completely. In a large bowl, whisk together the sugar and egg whites until blended. Place the bowl over a saucepan of simmering water and whisk until mixture reaches 140 degrees.

Transfer the egg/sugar mixture to a large bowl of a stand mixer with a whisk attachment and beat on low speed for 1 minute to cool slightly. Increase speed to high and beat for 4 minutes or until mixture is cool to the touch and doubled in volume. Reduce speed to low adding the soft butter by tablespoons and beat well after each addition, until all of of it has been added. Continue to beat until mixture looks smooth. Using a spatula, fold in the melted chocolate and the hazelnut extract and beat until fluffy.

I used it on this cake (hazelnut) for a friend's b-day earlier this year.

The cake and frosting look good. I like hazelnut.

IIRC, I think I ended up using hazelnut liqueur, because I found myself out of extract that day (but I'm RARELY out of cocktail 'supplies' at my house).