Spread the coffee grounds into a layer in the bottom of your mold.
Cut up the soap base into chunks and place it in a heat safe bowl.
Heat the soap base in the microwave for 45 seconds, then remove and stir. Continue heating and stirring in 20-30 second increments until the soap is fully melted. (Or use a double boiler to melt soap slowly)
Remove the soap base from heat and stir in the cocoa powder until combined.
Pour a layer of soap into the mold until it just covers the coffee grounds, then stir the grounds and soap together.
Pour the rest of the soap mixture into the mold and sprinkle lightly with extra cocoa powder.
Let the soap set until completely hardened, then remove it from your mold and cut it into bars with a sharp knife.
If you want a really clearly defined layered look to your bar, wait until the coffee ground soap layer is a slightly cooled before you add the final cocoa soap on top.