Place the butter into a saucepan and caramelize it on a medium heat. Stir it every now and then to prevent it from burning. Once some color starts to form turn down the heat to get more control. You want a nice golden brown color. Place it to the side.
Then mix the whole egg with the sugar and the zest from the lemon. Now cut the vanilla pod in half and scrape out the seeds. Add the seeds to the bowl and start mixing till you have a fluffy mixture. This takes a couple minutes.
Then while mixing add the flour, the baking powder and the beurre noisette we just made. You’ll end up with a thick fluffy batter.
Now fill a greased madeleine mold for 3/4 and bake it at 190 degrees Celsius till golden on top. This takes around 6 to 8 minutes.
