Spray the baking pan with baking spray or brush with butter and sprinkle with some flour. Tap out the excess flour.
Sift twice all-purpose flour, salt, and baking powder.
Place butter, sugar, zest, and vanilla into the bowl of your electric stand mixer with a paddle attachment on.
Beat on medium high for 5-7 minutes. Add your egg yolks and eggs in 2 additions. Mix just until incorporated. Add your dry ingredients in 2 additions. Mix just until incorporated, don’t over mix.
Put the mixture into a sturdy pastry/piping bag and refrigerate for 30 minutes.
Preheat oven to 350°F.
Pipe batter into the madeleine pan as shown on the picture. Do not overfill. Butter will be a bit tough. To help ease squeezing it out of the pastry bag work the bag with your hands for a few seconds and start piping the butter.
Bake 10-15 minutes until light golden color on the sides. Let cool.
Sprinkle with powdered sugar.
Store at room temperature in an airtight container for up to 3 days.