Classic madeleines—those perfectly delicate shell-shaped cookies—are flavored with lemon or orange zest, but variations include chocolate, cocoa, almond paste, or nuts. Baked in scallop-shaped molds, these cookies are tender with a tight-grained interior and a delicate crust. 
 
Ingredients  
8  tablespoons (1 stick) unsalted butter, plus more for pan    
5  tablespoons all-purpose flour, plus more for pan    
1/2  cup whole hazelnuts, toasted    
1 1/4  cup confectioners’ sugar, plus more for dusting 
Pinch of salt    
4  large egg whites    
1/4  teaspoon pure vanilla extract
 
Directions 
1.   Heat oven to 325*F. In a small saucepan, melt butter until light amber in color. 

2.   Brush madeleine pan with melted butter, and dust lightly with flour. Place hazelnuts and 1 tablespoon confectioners’ sugar in the bowl of a food processor fitted with a steel blade, and process until very fine.
 
3.   Combine hazelnut mixture, 1 cup plus 3 tablespoons confectioners’ sugar, flour, and salt in a medium bowl. Add egg whites and vanilla, and whisk to combine. Add melted browned butter, and whisk until incorporated. With a tablespoon, fill molds evenly, about three-quarters of the way. Transfer to oven, and bake 14 to 18 minutes. Cool 2 minutes, and remove from pan. Cool completely on a rack, ridged side up. Dust cookies with confectioners’ sugar.  Makes 24 large cookies.  

Source: www.marthastewart.com 
Photo: Todd Atkinson