Melt the butter over medium heat and let it cool.
In a bowl, whisk together the eggs and sugar.
Sift in cake flour, baking powder, and Earl Grey tea powder.
Add the melted butter and mix well.
Let the batter rest in the refrigerator for at least 30 minutes.
Butter the madeleine molds and fill them up to 80% with batter.
Bake in a 170°C oven for 12–15 minutes.
Remove from the molds and let cool.