Madeleines

3/4 cup flour
1/2 teaspoon baking powder
2 large eggs
1/2 cup sugar
2 teaspoons finely grated lemon zest
2 teaspoons vanilla extract
5 tablespoons unsalted butter, melted and cooled

Butter and flour a madeleine pan with 12 cavities.
In a small bowl, combine the flour and baking powder. Set aside.
In the bowl of an electric mixer, whisk the eggs by hand. Whisk in the sugar in a stream. Whisk in the lemon zest and vanilla.
Place the bowl on the mixer fitted with the whisk attachment and whip the mixture on medium-high speed until it is light and fluffy, about 2 to 3 minutes.
Remove the bowl from the mixer and fold in the flour mixture. After the flour has been absorbed, fold in the butter.
Cover the bowl and chill 3 hours or overnight (this helps them develop the characteristic humps on their undersides, but you can proceed immediately to the baking if you don’t mind them being flat).
When you are ready to bake, preheat the oven to 400 degrees.
Use a spoon to fill each cavity of the pan about ¾ full.
Bake the madeleines until they are light golden and feel firm when pressed with a fingertip, about 10 to 12 minutes.
Invert the pan onto a work surface and gently bang one of the sides of the pan to help the madeleines fall out, then transfer them to a rack, grooved side up, to cool completely.