Preheat the oven to 170°C (338°F).
Put eggs and sugar in a bowl and mix.
Add milk and green tea powder, and mix well.
Sift in flour and baking powder and mix.
Add melted butter to finish the batter.
Pour the batter into a cake mold.
Bake in the 170°C oven for 30 minutes.
Let it cool and serve.