Grease 2 3" ramekins or similar form.
Melt 100g marshmallows, 1 tbsp butter and a pinch of salt over low heat, stirring til fully melted and bubbling slightly.
Remove from heat; add 50g rice krispies and stir til combined.
Split into ramekins. Press down halfway with a greased spoon, top with chocolate chips, and finish pressing down til compact and round. Let cool til solid enough to handle
Preheat broiler. Remove from ramekins. Top with fluff. Broil for 45 seconds on top rack.