Any time you set out to make cake — especially a foam-based sponge cake like joconde — it’s very important that you have all your ingredients pre-measured and at-the-ready. You also want to have all your ingredients at room temperature.
Begin by brushing melted butter on your parchment-lined sheet pans. If necessary, trim your parchment a bit so lies completely flat on the pan.
Now for the egg foam. Whip your six egg whites to soft peaks, then add the sugar.
Keep whipping until they’re at stiff peaks like so:
Remove the finished meringue from the mixer bowl to another bowl.
Rinse and dry the mixer bowl, and sift your powdered sugar into it.
Add your eggs and ground almonds…
…and with the paddle attachment, beat the mixture on medium-high until it’s light and foamy, about three minutes.
Now add your flour and stir on low for just a few moments until it’s gone.
Now it’s time to incorporate the meringue. Fold it in, adding the foam in three additions. Use the largest rubber scraper you’ve got.
Fold until there are just a couple of small lumps left, then fold in the melted, clarified butter. The mixture will look about like so:
Pour the batter into your prepared pans, dividing it evenly. If you’re the type that likes to use a scale for this sort of thing — and I am — you’ll pour about 18 ounces of batter into each pan. Spread the batter as evenly as you can, paying special attention to the corners.
Bake 6-9 minutes, until the joconde layers look about like this:
Let cool for maybe a minute, then using a sharp knife, gently loosen the cake from the sides of the pan. If you can, lift the corners of the parchment up a bit to make sure the joconde sheet is loose all the way around.
Apply a fresh sheet of parchment to the top of the layer.
Flip the pan over…
Remove the pan and very gently and carefully peel the parchment off the top of the cake.
Flip the parchment sheet over and put it back on the cake, then move the layers to a wire rack and cool about 15 minutes. Done!