Ski, the buerre noisette isn’t difficult. Just put the butter into a pan, cover with a lid ajar so the moisture can escape, and turn the heat on medium. It probably takes around 5 minutes and there can be some splattering (hence the lid). As you watch it, the foam will subside and the solids will drop to the bottom of the pan, then turn brown. If you make a little extra, say 1T, you can just pour off the butter and leave the solids in the pan, no filter required. If it cools too much by the time you are ready to use it, just give it few sconds in the microwave- it should be liquid but not hot when you fold it in.
Some other tips:
I’m sure you’ll weigh the yolks, but they have gotten smaller since this recipe was created and it now takes 14 to make this cake, not 12.
When warming the eggs, don’t go past 110F, and a little cooler is recommended by some chefs.
Beat five minutes on high, then switch to medium for a few minutes longer to help further stabilize the foam (provided you have a Kitchen Aid or similar- for a hand mixer just beat 10-12 minutes on high).
And sift the flour like it says, especially when you are putting it into the bowl of egg foam.
For folding, use a slotted spoon or large whisk, and it’s not a bad idea to make one or two passes with a spatula to scoop up the heavy butter off the bottom of the bowl.
For your mousseline, I recommend making Rose’s Apricot puree, it’s not difficut and is soooo good. Add about 2/3 cup along with 2 tsp vanilla to your mousseline, and if you have the apricot eau de vie you can add that as well (start with an ounce or two). With all of the flavorings, you can add more to taste but remember that the cake is delicate and you don’t want to overwhelm it.
Assemble the cake a day ahead of serving (especially if sprinkling with liqueur, as in the Golden Cage showcase cake) and bring to room temp a couple of hours before.
You’ll love having this cake in your bag of tricks, genoise is the category of cake that transformed me from “not really a cake person” to an ardent lover of cakes! It’s nearly always my choice for a layer cake.