Preheat oven to 350°.
Beat butter and sugars at medium speed with paddle attachment of stand mixer until creamy.
Add eggs and 1 1/2 tsp. vanilla, beating until blended.
Add flour, baking soda, and salt and beat until blended.
Fold in chocolate by hand just until combined.
Using a 1 tablespoon capacity cookie scoop, place cookie dough balls on parchment paper-lined baking sheets.
Bake for 8 minutes, you want them slightly underbaked as they will cook more in broiler.
Remove from oven and top each with half a marshmallow.
Broil just to brown the tops-watch closely.
Let cool 3 minutes.
Drizzle on melted chocolate and top with graham crumbs! Mmmmm!