Preheat the oven to 375 degrees and prepare two cookie sheets with silicone baking pads or parchment paper. 

Whisk together the flour, graham cereal crumbs, baking soda, and salt and set aside.

In a medium sized mixing bowl, cream together the butter and sugars until light and fluffy. Add the egg, cream, vanilla and beat well. Mix in the dry ingredients until the dough is well combined. Stir in the chocolate chips by hand. 

 Using a cookie scoop, arrange the cookies on the baking sheet 2 inches apart and bake for 8-9 minutes or until golden brown. 

While the cookies bake, cut the large marshmallows in half with a pair of kitchen scissors. As soon as the cookies are baked, remove them from the oven and press one large marshmallow cut side down onto the top of each cookie. 

Place the cookies back into the oven for another 90 seconds to 2 minutes until the marshmallows are puffed and toasty. Remove from the oven and let cool. Drizzle with chocolate if desired.