Green tea marbled madeleines

I made these as a variation from the yuzu madeleines recipe. These madeleines did not turn out as good.... I wonder if it's coz of the green tea powder.

Also, the green tea taste was not prominent enough. Maybe I have to add more to it. I used 1 tbsp and yet the taste was still not what I wanted.

The marbling was achieved by the addition of bamboo charcoal powder. As seen, not enough of the bamboo charcoal powder was added, it turned out like greyish instead of black.