Brush madeleine pan with melted butter and dust lightly with flour.

In a bowl, beat eggs and sugar until pale and fluffy (about 3 mins).

Stir in lemon zest, juice, Greek yogurt, and vanilla extract.

In a separate bowl, whisk flour, salt, and baking powder.

Gently fold dry ingredients into the wet mixture.

Fold in melted butter until combined.

Chill batter for at least 1 hour.

Preheat oven to 375°F (190°C).

Fill each mold about ¾ full.

Bake for 10–12 minutes until golden and puffed.

Cool for 5 minutes, remove from pan, and serve.