Heat a large skillet or griddle over medium heat. Add a tablespoon or so of butter to the griddle.
In a bowl, whisk together the eggs, half and half, vanilla extract, cinnamon and salt. Dip each piece of bread in the mixture until it’s coated on both sides. Dip it in the graham crumbs and press gently so the crumbs adhere to all sides. Place it on the buttered skillet. Repeat with remaining bread. Cook until the sides of the toast and golden brown and set. Place the french toast pieces on a baking sheet.
Heat the broiler in your oven to high. Sprinkle a bit of chopped chocolate on the toast, then cover each piece with mini marshmallows. Add a bit more chopped chocolate over top. Place the sheet with the toast until the broiler and broil just until the marshmallows are golden. Don’t remove your eyes from the toast! It will only take 30 seconds or so.
Serve the toast immediately. You can serve it with maple syrup if desired – but I melted a little bit of the leftover chocolate and drizzled it on top!