Easy - for beginners
Preheat the oven to 400°F. Lightly grease and flour madeleine molds or mini-muffin tins. Melt the butter in a small saucepan and set it aside until it reaches room temperature.
Mix the almond flour 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.
Bake the madeleines 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 from the molds.
Once cooled, madeleines can be kept in an airtight container at room temperature for up to one week.