Preparing to bake. Preheat the oven to 400 degrees F. Lightly grease and flour financier molds or mini-muffin tins. Melt the butter in a small saucepan and set it aside until it reaches room temperature.
Making the batter. Mix the almond fl our with the cocoa powder, salt, and powdered sugar. Stir the egg whites and almond extract into the almond mixture, then gradually stir in the melted butter until incorporated and smooth. Spoon the batter into the molds, filling them three-quarters full.
Baking the financiers. Bake the financiers for 10 to 15 minutes, until the cookies are slightly puffed and springy to the touch. Remove them from the oven and let cool completely before removing the financiers from the molds.
Suggestions. Once cooled, financiers can be kept in an airtight container at room temperature for up to one week.