Preheat the oven to 350ºF.
Slice each marshmallow in half and set aside.
In a medium-sized bowl, combine the flour, sifted matcha powder, baking soda, baking powder, and salt.
In a separate large bowl, beat the butter and sugar until lighter in color.
Add the egg and vanilla. Beat until light and fluffy.
Add the dry ingredients and mix with a rubber spatula until fully combined.
Roll pieces of dough into 1.5-inch pieces.
Flatten the dough ball slightly, form an indent in the middle, and place a halved marshmallow in the center.
Push the dough back around the marshmallow to seal it inside and re-roll into a ball.
Roll each piece of dough in the extra 1/4 cup of sugar.
Bake a 3 inches apart for about 10 minutes or until the tops have cracked.