Beat eggs and sugar with electric mixer on high speed until light and fluffy.
Add grated lemon skins, and mix to combine.
Add melted butter slowly to the egg/sugar mixture.
Add dry ingredients slowly to the above mixture on very low speed. Mix until just blended, but do not over mix.
Refrigerate mix for at least 4 hours before using.
Preheat over 375F (325F for convection)
VERY generously butter madeleine molds. Then spoon mix into the molds, filling each cavity about 2/3 full.
Bake until golden brown on the edges and classic” hump” develops in the middle. cakes are done when touched in center and cake springs back. Immediately turn out the cakes on a cooling screen.
To reuse the pans: wipe each cavity thoroughly with paper towel, rebutter and use again. Note: Yield will vary depending on size of Madeleine molds. Unused mix can be frozen or kept covered in the fridge for up to 10 days.