Melt chocolate gently either in a double boiler or gradually in a microwave.
When chocolate has melted, arrange half of the kettle corn and marshmallows in a layer in a 9x13 casserole dish.
Drizzle half of the melted chocolate over the kettle corn and marshmallows.
Repeat steps 2 and 3 once more.
Sprinkle coarse salt over the top.
Refrigerate uncovered for 10-15 minutes or until the chocolate hardens. Seal tightly with plastic wrap to bring to the party along with a serving spoon for partygoers to scoop out.