Combine eggs, both kinds of sugar and salt in a bowl. Work lightly with a spatula until light in colour.
Sift together flour/baking powder. Fold gently into mixture with vanilla if using. Do not overwork the mixture.
Pour in melted butter/honey and mix. Cover bowl with clingfilm and leave for 30 minutes.
Grease insides of madeleine tins. Pipe the mixture into the tins.
Bake for about 5 minutes (smaller ones) and 10 minutes (larger ones) on the middle shelf of the roasting oven if you have an Aga. Do not overcook or they will be too dry.