Melt the 1/2 cup of butter in a large bowl and set aside to cool slightly.

In a separate bowl, beat the eggs and granulated sugar on high speed for about 8 minutes until thick, pale, and forming ribbons.

Beat in the lemon zest and vanilla extract until fully combined.

In a small bowl, whisk together the flour, baking powder, and salt.

Gently fold the flour mixture into the egg mixture using a silicone spatula.

Stir 1/4 cup of the batter into the melted butter, then fold the butter mixture back into the remaining batter.

Cover the batter with plastic wrap and chill in the refrigerator for 30-60 minutes.

Preheat your oven to 350°F (177°C) while the batter chills.

Brush the madeleine pan with the remaining melted butter.

Spoon a generous tablespoon of batter into each scalloped well in the pan.

Bake in the oven for 10-12 minutes or until the tops spring back lightly when pressed.

Invert the pan onto the counter and transfer the warm madeleines to a wire rack. Dust with confectioners’ sugar before serving, if desired.