Preheat oven to 350 degrees F. Line two large baking sheets with parchment paper.
In a small bowl, whisk together the flour, cocoa powder, baking powder, baking soda, and salt.
In a mixing bowl with the paddle attachment attached, beat the sugars and margarine together until smooth (or use a hand mixer). Add the non-dairy milk, and mix together a minute or two.
In a small bowl, whisk together the flour, cocoa powder, baking powder, baking soda, and salt.
On low speed, mix the flour into the batter in 3 portions. Stop the mixer and scrape the sides of the bowl with a spatula after every addition of the flour. On low speed (or fold in by hand with a wooden spoon), mix in the chocolate chips and half of the marshmallows.
Chill the dough for about 20 minutes.
When ready to bake, scoop the cookie dough onto parchment-lined baking sheets into 1.5 tablespoon balls spaced a couple inches apart, on each of the baking sheets.
Hand place the rest of the marshmallows in the cookies, tucking them into the cookie dough on top.
Bake for 10-15 minutes or until edges begin to firm up. The cookies will still look soft. They will continue to cook as they cool. Let cool for 5 minutes before removing from pan. These cookies are wonderful warm. If you have a microwave, you could f your eating them after they have cooled you can warm them in the microwave for 10 seconds.
Cookies will get more crispy on the edges as they cool down.