I'm expanding my buttercream horizons, as it is a standard cake filling and glue for fondant.
In the Snowflake Cake, (see First Fondant Foray) I played it safe and used American buttercream. Nothing magical: butter and confectioners' sugar, mostly. (Icing sugar, powdered sugar, etc - whatever you want to call it.) Tasted ok, no complaints.
So there are French buttercreams, Italian, Swiss, and just what is mousseline? Most call for cooking something: a simple syrup, egg yolks, etc. Guess I'll just start trying them and see what works out the best. Looks like my instant-read thermometer will be handy.
Cake 1, Buttercream 1: Frosted a White Spice Pound Cake with Neoclassic Buttercream. (Both recipes from Rose Levy Barenbaum's The Cake Bible. I made this buttercream with my hand mixer.) The taste and texture are far superior to American buttercream. However, I didn't actually get to taste the frosted cake: Cake Practice Day = chaos. After several hours of sitting out in a bowl, the Neoclassic Buttercream separated, became a much darker yellow and slimy. Yum! (Not really.)
Cake 2, Buttercream 1: Used the Neoclassic Buttercream between the layers of the Velvet Devil's Food Cake from Cook's Illustrated's Baking Illustrated. Attempted to make a crumb coat for the Devil's Food cake too, but watering down the Neoclassic Buttercream did not end well.
Cake 2, Buttercream 2: Day after Cake Practice Day, I made the Mousseline Buttercream (also from The Cake Bible) to cover the Devil's Food cake. A fine time to use the fabulous Kitchenaid stand mixer that my mom so thoughtfully and generously gave to me about six weeks ago. (Thanks, Mom!)
The Mousseline Buttercream seemed to turn out as described, maybe a little more dense than I expected. The texture and taste were far superior to the Neoclassic Buttercream, and really the American buttercream shouldn't even be allowed on the playground. But it is a finicky recipe, requiring a lot of temperature checking.
This batch o' buttercream ended up sitting in the bowl for about 20 minutes after I finished making it. Went to slather on a crumb coat for the Devil's Food cake, but it looked like the buttercream was sort of weeping... uh oh... another whirl in the Kitchenaid... EEK! DISASTER! A liquid substance (egg whites? Vanilla extract?) continued to leach from the buttercream, and it looked like grey, dirty dishwater. It was so gross! Crap. That's a lot of ingredients to chuck out.
I think this mishap was due to the Kitchenaid beater, but I plan to check with Kitchenaid. The beater attachment for the 6qt mixer isn't enameled like the 5qt beater used to be. I don't know what kind of coating it has, but it's not uniform, it almost looks tarnished. When I washed the beater after the buttercream debacle, I got the same grey-yuck color on the dish sponge. I am displeased. It is a bit of a set back.
Cake 2, Buttercream 3: Ended up using a 1/4 batch of Peggy Weaver's (American) Buttercream I recipe on the Devil's Food cake, which was somewhat smoother than the one I used previously. Still no contest with the Mousseline Buttercream, though.
Bottom line: Neoclassic Buttercream will probably separate in the summer heat. Don't water down frostings for crumb coats, just use a thin thin thin layer of the frosting and refrigerate the cake until the crumb coat hardens. My Kitchenaid beater sabotaged my buttercream! But I can make buttercream with my hand mixer, sort of. American buttercream is only good as a last resort.