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.
To assemble:
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!