Whisk the eggs with the sugar and salt for 3-4 minutes until pale and fluffy.
Add the lemon zest, then the flour mixed with the baking powder, and fold in gently with a spatula.
Finally stir in the lukewarm butter until you have a smooth, glossy batter.
Cover the batter and chill for at least 1 hour — the difference between the cold batter and the hot oven is what makes the madeleine's typical 'hump' rise.
Preheat the oven to 200 °C. Butter and flour the madeleine tin and fill the moulds three-quarters full.
Bake for 8-10 minutes until the edges are golden and the centres have humped up. Turn out at once and cool on a rack.
A Receptnaptár original recipe. Calories and protein are estimated.