Preheat the oven to 425 F.

Brush the financier molds with butter and refrigerate or freeze to harden the butter.

Place the sugar in a large bowl and whisk to break up any lumps.

Add the all-purpose flour. Sift the almond flour and whisk to combine.

Make a well in the center of the dry ingredients.

Pour in the egg whites and vanilla, gradually incorporating the dry mixture until all the dry ingredients are well-combined.

Scrape down the sides and bottom of the bowl,whisk again and set aside for now.

Brown Butter: Place the butter in a saucepan over medium-low heat. You'll need about 300 g or 22 tablespoons of unsalted butter. Start whisking slowly to keep the particles suspended in the butter. Keep cooking until the liquid is a golden, nutty brown, then strain through several layers of cheesecloth or a superfine sift. Finally, measure out the correct amount of hot browned butter.

Whisk in the brown butter in 2 additions.

Transfer the batter to a pastry bag or use a spoon to pipe or spoon the batter into the prepared mold stopping 1/4 inch from the top.

Tap the bottom of the molds against the work surface to smooth the top of the batter.

Place the pan in the oven, lower the oven temperature to 350 F and bake for 20-25 minutes or until the tops are golden brown and a skewer inserted in the center comes out clean.

Immediately unmold the financiers and cool on a cooling rack.

Dust with powdered sugar.

Note: The financiers are best the day they are baked, but can be stored in a covered container for one day.