Chocolate Biscuits, such as LU Le Petit Ecolier
Place onto a cookie sheet the cookies for the s'mores
Top cookies with marshmallow(s). You can trim a very large marshmallow (as I have done in the photo) or add several mini marshmallows, you just want to be sure you do not add so many that the the cookie overflows with the marshmallow.
Toaster Oven: Broil low for 2 minutes (the photographed version used this method)
Oven: Pre-heat oven to 250 degrees. Bake for 8-10 minutes. Marshmallows will be soft but not brown. To brown, either toast with a torch or set oven to broil and place back into the oven under the broiler for a few seconds. Marshmallows will color very fast, so watch carefully.