Sift the flour, powdered sugar, cornstarch, matcha and salt together. Whisk in the coconut oil and almond extract in the center of the dry ingredients to form a paste, then gradually incorporate the rest of the dry ingredients. If dough is too crumbly, add additional water 1/2 teaspoon at a time.
Roll out dough to about 1/4" thickness. Score the cookies in a square pattern and use a fork to stab a few holes in each square.
Bake at 325 for 12-14 minutes, or until cookies are still soft to touch, but are just barely brown and set around the edges. Let cool before breaking along your scored lines.
Preheat broiler to 475 and place marshmallows on a small greased baking sheet. Broil until golden, keeping an eye on them the entire time. Sandwich each marshmallow between two cookies with a smear of pudding or a block of dark chocolate and eat!