I found this recipe from a Mandarin Website. It used Green Tea powder (Japanese "Mocha"), and the cake actually looked "greenish"....
- cool the butter under room temperature for a while, then mix the butter with sugar.
- Mix in eggs, one at a time.
- Sift in BP, Cake Flour, and Salt, mix well.
- Dissolve the Green Tea Powder in the milk, then add in the batter.
- Bake the cake with 180C (about 370F) temperature, for about 30-35 minutes.