Preheat oven to 375 deegrees F. Line a cookie sheet with parchment paper.
In a large bowl, cream butter and sugar until light and fluffy.
Stir in eggs ,vanilla, and milk.
Mix in baking soda, vinegar, baking powder, and graham cracker crumbs.
Stir in flour a little at a time until just combined.
Drop batter onto pan using an ice cream scoop. Bake for 8-10 minutes or until a toothpick inserted in the center comes out clean. Allow to cool on pan for 2-3 minutes.
For the Buttercream
In a large bowl cream butter and marshmallow fluff. Stir in vanilla extract.
Gradually add powdered sugar a little at a time. Add milk as needed until you reach your desired consistency.
For the Ganache
In a microwave safe bowl, heat whipping cream for 45-60 seconds.
Fold in chocolate chips until smooth.
Spread approximately 1 tablespoon of both ganache and marshmallow buttercream onto half of the cookies. Top with remaining cookies.