Preheat oven to 425°F (or set broiler on high) and place a small oven-safe skillet or baking dish on a rimmed baking sheet.

Spread chocolate chips in the skillet and dot with butter if using.

Arrange marshmallows cut-side up around the chocolate or standing upright for even browning.

Bake 4–6 minutes until marshmallows are puffed and golden; broil 30–60 seconds if using broiler, watch closely.

Remove, sprinkle a pinch of flaky salt if you like, and serve immediately with grahams.