Preheat the oven to 350 degrees and prepare a baking sheet with parchment paper.
Using kitchen shears, cut large marshmallows in half and set aside.
In a medium bowl, mix together flour, instant pudding, graham cracker crumbs, baking soda and salt. Set aside.
In a mixer fitted with a paddle attachment, combine butter and sugars until light and fluffy.
Add eggs and vanilla and mix until combined. Add dry ingredients and mix until just combined.
Stir in marshmallows and 1 1/2 cups chocolate chips. Using a large cookie scoop, scoop out dough balls onto baking sheet.
With the palm of your hand or the back or a large wooden spoon, lightly press the dough down so it is flat.
Bake for 10-12 minutes, or until the edges turn golden.
Remove the cookies and place cut marshmallow, cut side down, in the center of the cookie and press down lightly.
Put back in the oven for 1- 2 minutes, or until the marshmallows begin to get gooey. Remove cookies from the oven and transfer to a wire rack to cool. Using a microwave safe bowl, melt remaining 1/2 cup of chocolate chips. Transfer melted chocolate to pipping bag and cut a small hole at the end. Place cooled cookies on a sheet of parchment paper, and pipe chocolate drizzle.