On a baking sheet lay out as many graham crackers as you like, both the tops and bottoms of the s'mores. Then place 2 marshmallows on half the crackers. Bake in the oven for approximately 4 to 5 minutes, watching closely until the marshmallows are golden brown.
Remove from the oven and take the toasted top crackers off the baking sheet and set aside.
Place 2 squares of chocolate on the marshmallows, gentle pressing into them. Bake again for another 1 to 2 minutes so the chocolate gets soft.
Remove from the oven and assemble with the top crackers. Get some napkins because they're gonna be messy!