Preheat the oven to 350 degrees F, and line two sheet pans with parchment paper.
In a large bowl, sift together the powdered sugar and cocoa powder. Whisk in the salt. Add the egg whites and vanilla and whisk until combined. Stir in the chocolate chips and almonds.
Use a small ice cream scoop to portion out small mounds on to the parchment paper, then top each cookie with 4-5 marshmallows. Pop into the freezer for 5 minutes to chill slightly (this prevents them from spreading too much in the oven).
Bake for 12-13 minutes until the marshmallows are golden brown. Let the cookies sit on the paper for a few minutes to set, before moving them to a wire rack to cool.