-
1
Sift the flour, cocoa, baking powder and salt together.
-
2
Working with a stand mixer fitted with the whisk attachment or with a hand mixer in a large bowl, beat the eggs and sugar together until pale and slightly thickened, about 3 minutes. Beat in the vanilla extract, then switch to a rubber spatula and gently fold in the sifted dry ingredients, followed by the melted butter. Put a piece of plastic wrap directly against the surface of the batter and refrigerate for at least 3 hours or for up to 2 days. Chilling the batter gives you a better chance of getting the characteristic hump on the back of the cookies.
-
3
Center a rack in the oven and preheat the oven to 400u00b0F. Generously butter 12 full-size madeleine molds, dust the insides with flour and tap out the excess. Butter and flour or spray the pan even if it is nonstick; skip this step if you are using a silicone pan. Place the pan on a baking sheet.
-
4
Spoon the batter into the molds.
-
5
Place the pan in the oven and immediately lower the oven temperature to 350u00b0F. Bake the cookies for 13 to 15 minutes, or until they feel springy to the touch. Remove the pan from the oven and rap one side of the madeleine pan against the counter-the plump little cakes should come tumbling out. Gently pry any reluctant cookies out with your fingers or a butter knife. Cool to room temperature on a rack.
-
6
Fit a small pastry bag with a small plain tip and spoon the fluff into the bag. Use the point of the tip to poke a hole in the rounded (plain) side of each madeleine, and pipe enough fluff into each cookie to fill it-stop when the fluff reaches the top of the cake. (You'll use only a bit of fluff.)
-
7
Put the chocolate in a small deep heatproof bowl. Bring the heavy cream to a full boil, then pour it over the chocolate. Wait for 1 minute, then gently whisk the cream into the chocolate: start at the center and slowly work your way out in concentric circles until you have a smooth, shiny mixture. Gently whisk in the butter.
