Preheat the oven to 400°F
Line a baking sheet with parchment paper or foil
Place graham cracker halves on the baking sheet
Top each graham cracker half with a piece of chocolate
Place a marshmallow on top of the chocolate
Bake for 3 to 5 minutes until the marshmallow is puffed and lightly golden
Remove from the oven carefully
Top with another graham cracker half
Press gently and serve immediately