I tried several online recipes before adapting my own. I changed two major aspects of the traditional madeleine recipe. First, combining the butter, sugar, and egg before adding the flour keeps you from over-mixing and getting a rubbery texture. Also, increasing the cooking temperature increases the leavening and produces the right texture. Where I think that I haven't gotten it just right yet is using the silicone pan. Everyone recommended silicone, but it doesn't produce the crisp edges I am hoping for. I'd like to get the metal pan and play with this some more.
10 tablespoons of room temperature salted butter or Fleichmann's Margarine
2/3 cup sugar
2 large eggs and one egg white
1/2 tsp. vanilla extract or other flavoring (optional)
1/2 tsp. grated lemon zest (optional)
1 cup all purpose flour
Preheat oven to 425 degrees Fahrenheit. Beat sugar and butter (or margarine) together until fluffy (about 5 minutes). Add one egg and beat until combined. Then add the remaining egg, vanilla, and lemon zest and combine thoroughly. Fold in flour until just combined. Place silicone pan on a metal cookie sheet to prevent flexing. Spoon 1 tablespoon of batter into each mold. Bake until golden brown and set, about 10 minutes. Yields 2 dozen.