Preheat the oven to 350°F.
In a mixing bowl, whisk together the flour, baking powder, matcha powder, and salt. Set aside.
Using another large mixing bowl, cream together the butter and sugar until smooth. Add in the egg and milk and mix well. Whisk in the dry ingredients mixture and mix until smooth and no lumps remain.
Place baking cups in muffin pan, and pour the batter in each cup. Top off with white chocolate chips.
Bake in the oven for 35-45 minutes, or until a toothpick comes out clean. Cool for a bit and enjoy! (I highly recommend having them warm)