Preheat the oven to 240 °C.
Start by making the beurre noisette: place the butter in a saucepan and melt. Keep on the heat until the butter has turned a light brown colour and has a warm, nutty scent. Remove from the heat and immediately pass through a sieve before leaving to cool down.
Use an electric whisk to beat together the eggs and the sugar until fluffy and creamy. Slowly mix in the flour and then the melted butter. Transfer the mixture to the fridge.
Grease your madeleine moulds and then fill each one with the madeleine mixture. Transfer to the oven and bake for 6 minutes (reduce cooking time to 4 minutes if making mini-madeleines).
«Make sure that the madeleine mixture is cold before transferring to the moulds: this will help the middle of the madeleine to rise and give the characteristic madeleine shape! Add a little lemon zest, honey, or vanilla to your mixture to add a different flavour.»