Melt butter in microwaveable bowl. Skim off foam from surface; keep warm. Sift together the flour, baking powder and salt; set aside.
In medium bowl, combine eggs and granulated sugar. Whip on high speed with electric mixer until thick and lemon-colored, about 3 minutes. Fold in orange zest. Gradually stir in warm butter. Fold in flour mixture. Cover and refrigerate 15 minutes.
Preheat oven to 325°F. Spray Madeleine pan with vegetable pan spray with flour. Spoon about 1 tablespoon batter into each cavity. Bake 13-14 minutes until Madeleine are firm to the touch. Remove pan from oven and immediately turn pan over onto cooling grid; gently tap pan to release Madeleines.