How to Make It
Preheat the oven to 350°. Generously brush madeleine molds with some butter.
In a medium bowl, combine the flour, cornmeal, sugar, lemon zest, cream of tartar, baking soda and salt. In another bowl, slightly beat the egg. Whisk in the cream and vanilla, then add 2 tablespoons of the melted butter. Add the cream mixture to the dry ingredients and mix just until blended. Spoon the batter into the molds, filling them half way.
Bake for 10 to 12 minutes, or until the cakes spring back when pressed lightly. cool briefly, then loosen with the point of a table knife and let cool on a rack.