In a large bowl or stand mixer, beat the softened butter, brown sugar, and cane sugar. Once combined, add in the egg, vanilla and mix it all.
Slowly add in the flour until mixed well. Add in the baking powder, fold in well using a spatula. Finally, add in the chocolate chips and fold in once again.
Scoop out the cookie dough using an ice cream scooper. Using your thumb, form a hole in the center and place a whole marshmallow inside. Press it down and cover using your fingers.
Place cookies on a prepared baking sheet making sure they are about 2 inches apart.
Bake for 11-13 minutes. Allow the cookies to cool for 10 minutes or enjoy them right away!
Video
Notes
If you want to reduce the sugar content, split the marshmallow in half or use mini marshmallows.