Prepare the batter – In a large bowl, whisk eggs and sugar together until the mixture becomes pale and fluffy.

Add flavors – Stir in vanilla extract and lemon zest for added aroma.

Mix dry ingredients – In a separate bowl, sift together the flour, baking powder, and salt.

Combine wet and dry – Gradually fold the dry ingredients into the egg mixture using a spatula to maintain the light texture.

Add melted butter – Slowly pour in melted butter and milk, folding gently until fully incorporated.

Chill the batter – Cover and refrigerate the batter for at least 1 hour (or overnight) to enhance flavor and texture.

Prepare the mold – Preheat the oven to 375°F (190°C). Grease the madeleine mold with butter and lightly dust it with flour.

Fill the molds – Spoon the batter into each shell mold, filling about three-quarters full.

Bake – Bake for 8-10 minutes or until the edges are golden brown and the signature hump forms.

Cool and serve – Remove from the oven, let cool for a few minutes, then transfer to a cooling rack. Dust with powdered sugar before serving.