Preheat the oven to 230½C/450½F/gas mark 8. Butter and flour some madeleine moulds. These are very shallow, fluted and an elongated shell shape. If you use bun tins, the mixture will fill twelve, not twenty-four and you will not, of course, get the same shape as a madeleine.
Sift together the dry ingredients. Beat in the eggs, and then mix in the melted butter and zest. Pour the batter into the prepared moulds, and bake in the top half of the oven for 5 to 7 minutes.
Remove from the oven once the madeleines are golden well risen.