Preheat the oven to 350°F (175°C). Lightly spray a mini muffin pan with nonstick cooking spray.
Scoop about a tablespoon of cookie dough into each cup and press to form a well in the center.
Bake for 10-12 minutes, until edges are golden brown.
While cookies bake, cut marshmallows in half crosswise.
Remove cookie cups from oven. Immediately press one piece of chocolate into each center, then top with half a marshmallow (cut side down).
Return to oven and bake for an additional 2-4 minutes, until marshmallows are soft and slightly golden.
Cool in pan 15 minutes before removing. Sprinkle with graham cracker crumbs and add extra chocolate pieces on top if desired.