PREP BROWNED BUTTER (beurre noisette) FIRST: Cook the 150g (10 tablespoons) butter in a small sauce pan over medium heat for about 10 minutes. Cover loosely with a folded piece of aluminum foil because the water content of the butter causes it to pop and splatter. After 5 minutes, the butter will be foaming. Watch closely the second 5 minutes. As the butter continues to cook, the milk solids in the butter will brown and drop to the bottom of the pan; the butter will turn a golden brown. Skimming off the foam will allow you to better see the bottom of the pan. Turn off the heat after about 10 minutes when the solids in the bottom of the pan reach a nut brown. Immediately strain through a fine mesh sieve. Weigh out the 115g (1/2 cup) needed for the recipe and let cool.
BEAT the egg whites In the Kitchen Aid mixer on medium speed until frothy, using the paddle. Gradually add half the sugar with the mixer running. Turn off mixer.
WHISK the other half of the sugar with almond flour, hazelnut flour, all-purpose flour, and salt. Sift the flour mixture through a tamis, then add to the egg whites and sugar in the mixer. Mix on medium speed (#5) for 5 minutes until light in color.
ADD the cool beurre noisette and almond extract.
MIX 1 more minute. Scrape down sides and bottom of bowl.
REFRIGERATE until ready to bake. Tastes better after 2-3 days in refrigerator. Will keep refrigerated for up to two weeks.
USE for any recipe that calls for Financier Batter.
TO BAKE OFF MINI FINANCIER CAKES (Petits Fours): Use cold batter straight out of the refrigerator. Pipe or scoop into desired pans or molds, sprayed with a non-stick spray (Pam with flour), filling about half full. Bake @ 375° F (190° C) until golden brown and firm to touch. Let settle in the pans about 5 minutes before unmolding. Serve warm.