In a bowl or tray of cold water, soak the gelatin until softened, about 5-10 minutes. In a small cup, mix a couple tablespoons of the cream with the matcha powder. Stir very well with a fork until all of the clumps have been removed and you have a smooth, green mixture.
Heat a pot on medium-low flame, add the cream, vanilla, sugar, honey and salt and stir with a whisk. Add the gelatin (be sure to let the water drip off of it), and whisk until all of the gelatin has dissolved. Do not allow the mixture to get too hot / close to a boil; it will collapse the gelatin and your panna cotta will be soupy.
Turn the heat off and gradually whisk in the matcha mixture. Once thoroughly mixed and there are no clumps or air bubbles, pour gently into individual cups. Cover with saran wrap and chill overnight.
If you don't have small cups, you can lightly oil the inside of a cake pan, and the next day carefully place a plate on top, flip it, loosen the panna cotta from the pan and serve it sliced, like a cake.