Line your mini muffin tin with 20 mini muffin liners to prepare for the cups.
Chop the dark chocolate bars into small pieces if not using chips. Melt the chocolate slowly using a double boiler or microwave in 30-second bursts, stirring between until smooth and glossy. Avoid overheating.
Gently fold the crispy rice cereal into the melted chocolate until each piece is well-coated.
Spoon the chocolate and cereal mixture evenly into the prepared muffin liners. Fill each generously but avoid overfilling.
Sprinkle a small pinch of sea salt over the top of each cup while the chocolate is still soft.
Place the muffin tin in the refrigerator and chill for 30 minutes to an hour until the cups are fully set.