Melt the butter gently over low heat, then set aside to cool slightly. In the bowl of a stand mixer bowl whisk the eggs, sugar and vanilla until the mixture is light and foamy.
Whisk the flour, almond meal and baking powder in a separate bowl to remove any lumps. Gently fold the flour and almond meal mixture into the whisked eggs little by little until everything is just combined.
Add the melted butter and gently mix. Transfer the batter to a container with a lid and place in the fridge for at least three hours (or overnight).
When you are ready to bake the madeleines, preheat the oven to 220 degrees Celsius and prepare your madeleine trays by greasing them generously with butter then a light dusting with flour.
Divide the batter between the prepared madeleine trays by filling each cavity until is it about 3/4 full. Do not over fill each cavity, mini madeleines only need 1 tsp of batter.
Reduce the oven temperature to 170 degrees Celsius and bake until the edges of the madeleines are lightly golden and they have risen. Mini madeleines will take 7-8 minutes in a metal tin and 8-9 minutes in silicone moulds.
Remove madeleines immediately from their trays and place on a wire rack to cool completely. Allow the madeleines to cool shell side up as they may stick to your wire rack a little.
If you have batter leftover or only one madeleine tray, place any remaining batter back into the fridge until you can re-grease and flour your madeleine trays and bake the remaining batter.
Makes about 70 mini madeleines. Madeleines are best eaten the day they are made, but can be stored in an airtight container for 2 days.