Madeleine is a classic traditional small cake from Lorraine region in northeastern France. What makes a 'true' madeleine from other versions is recognizable hump. Because the batter is chilled prior to baking. Indeed, approximately 15% of the CO2 gas is released in the cold stage. Eighty-five percent of the CO2 gas is released in the oven. The temperature difference between the oven and the batter creates a burst of steam that results in a hump.
Pro Tips: Do not overwork the egg-sugar mixture. Refrigerate batter for at least 2 hours to relax prior to baking. Use a pizza stone, or an empty baking tray that will be placed in the oven during preheating.
Melt butter and add lemon zest. Gently beat eggs with sugar (but do not overwork). Sift together flour and baking powder. Incorporate the sifted powders and warm butter with the egg mixture. Cover and refrigerate batter for a minimum of 2 hours.
Fill a pastry bag with a large plain pastry tip or if using a plastic bag, cut an inch off the tip. Pipe no more than 1 ounce of batter into each madeleine form. (Alternately, you can skip the pastry bag and use a tablespoon instead.)
Butter and lightly flour non-stick madeleine pans. Shake off excess.
Place oven rack and pizza stone (a baking tray can be used instead) 8 inches/20 cm from the bottom of the oven. Preheat conventional oven to 500ºF/260ºC (450ºF/230ºC if using a fan oven). Bake for 5 minutes, then lower temperature to 350ºF/180ºC and continue baking for an additional 6 to 7 minutes. Store madeleine in a sealed container, or freezer bags for a few days. Madeleine can also be kept frozen for a few weeks. Enjoy!