Put the eggs and sugar in a large bowl and using an electric mixer, whisk until thick and pale, about 6-8 minutes.
Put the flour and baking powder in a separate bowl and stir together to combine. sift a third of the flour mixture into the egg mixture, carefully folding to combine, then add the remaining mixture in two additions in the same way.
Take a large spoonful of the batter and add this to a small bowl along with the melted butter, mixing them together to lighten the butter.
Pour the butter mixture into the batter and gently fold together to combine. Press a sheet of clingfilm onto the surface of the batter, then put the mixture in the fridge and leave overnight for at least 8 hours (the batter can be kept in the fridge for up to 2 days at this point).
To make the lemon glaze, put the lemon juice and sifted icing sugar in a medium bowl. Mix together using a wooden spoon until you have a smooth pourable glaze. Press a piece of clingfilm onto the surface of the glaze until needed - this will help to prevent it forming a crust.
Grease a 12-hole madeleine pan and dust with a little flour, tapping out the excess.
Preheat the oven to 220C (200C fan oven)/Gas 7. When the oven is up to temperature, spoon the batter into the madeleine moulds, a teaspoon should be enough, don't overfill the moulds. You don't need to spread the mix out, this will happen as it cooks.
Bake for 10 minutes or until the edges have started to go brown. Remove from the oven and immediately turn onto a wire rack. Leave to cool for 10 minutes, before dipping in the glaze, coating fully.
Allow the excess to drip back into the bowl before setting on a wire rack over a piece of parchment to set.
Taking a pastry brush, dip it in the frozen raspberry powder and using your hand tap the brush so that the powder falls onto the wet glaze.
These are best served as close to baking as possible, they are great the day they are baked.