1) Using a KitchenAid Mixer with a whisk attachment, combine the eggs, sugar, salt, milk and vanilla extract. Whip on medium high speed for 3 minutes, until the batter is pale yellow and slightly thickened.
see picture 2
2) In a separate bowl, combine the cake flour and baking powder and sift together 3 times.
3) Gently and in stages, fold the cake flour into the egg foam. see picture 3
4) While carefully folding, slowly add the melted and warm butter.
5) Allow the batter to rest in the refrigerator for 1 hour.
6) Load a pastry bag with the Madeleine batter. Using a non-stick Madeleine Mold, pipe each shell 3/4's full with the batter. see picture 4
7) Bake at 450F degrees for 3 minutes, then reduce oven temperature to 375F degrees. Slightly prop open the oven door about 1", and continue to bake the Madeleines for an additional 6 minutes. see picture 5
8) Remove from oven and unmold them onto a wire rack to cool. Shell-side down.
** The perfect Madeleines should have a beautifully defined hump in the center.
** They are best eaten fresh from the oven, since their quality will diminish within 1 hour!