Line a baking sheet with parchment paper and preheat the oven to 350 degrees.
Arrange graham crackers on the baking sheet in a single layer.
In a saucepan, combine butter and brown sugar. Bring to a boil over medium heat, stirring constantly (about 3 minutes).
Remove from heat and pour over the graham crackers evenly.
Bake in the oven for 8-10 minutes until the toffee mixture bubbles and covers the crackers.
Remove from the oven and immediately press a piece of chocolate onto half of the graham crackers.
Let them cool completely before breaking into squares.
Pack in a container to take camping.
To use: roast marshmallows over a campfire and sandwich one between two graham crackers, one with chocolate and one without.