Melt butter in small saucepan, add lemon zest, lemon juice then set aside to cool slightly.
In electric mixer cream eggs, sugar and salt on medium speed for 10 minutes until thick and pale yellow color.
Sift flour and baking powder in small bowl.
With mixer on low, slowly add flour mixture and butter lemon mixture, alternating ingredients until just combined, keeping the batter light and airy.
Refrigerate for 2 hours or best overnight.
Preheat oven to 375 degrees.
Brush Madeleine pan with melted butter.
Fill each mold with about a tablespoon of batter filling the mold by two thirds.
Bake for 9 minutes.
Let cool slightly, dust with powdered sugar.
Best eaten immediately.
