Make marshmallow cream: Using a stand or hand mixer, beat 2 cups cream until stiff peaks form, 5 minutes. Add marshmallow crème and keep beating, 3 minutes. Stir in 1 cup mini marshmallows and set aside.
Make ganache: Heat remaining ¾ cup heavy cream until simmering. Remove from heat and pour over chocolate chips in a heat-proof bowl. Let sit 5 minutes, then stir until combined and creamy.
In a 9"-x-9" baking dish, spread a thin layer of marshmallow cream. Top with one layer graham crackers, then a thick layer of marshmallow cream, follower by a layer of ganache. Repeat layers until you reach the top (leave about ¼").
Garnish with remaining mini marshmallows, crushed graham crackers and chopped chocolate and cover loosely with plastic wrap. Refrigerate at least 4 hours or up to overnight.
When ready to serve, heat broiler. Broil 1 minute to toast marshmallows. Freeze 5 minutes to let set and serve.
Recipe by 5* trending recipes with videos at https://food.theffeed.com/2019/06/12/smores-icebox-cake/