Melt the chocolate in bain Marie and reserve.
Prepare a rectangular mold 20 cm x 28 cm with parchment paper.
Place a heavy bottom pot on the stove, when this is hot add the coconut oil, add the mashmellos, stir with a wooden spoon.
When the mashmellos begin to melt, add the toasted rice in small amounts and stir, add the melted chocolate, add nut (reserve chocolate and nut to add on top).
Remove the mixture from the stove and place the mixture on the mold and press it to get a compacted flat surface, then add the remaining melted chocolate and nuts on top.
Refrigerate, cool in the fridge for 30 minutes, then cut the bars