1. In double boiler over medium heat, stir together the chocolate chips, cream, and butter, until everything is melted and smooth.
2. Add the peanut butter and stir again until everything is blended well.
3. Pour mixture into shallow pan (an 8x8 baking pan or pie tin will do), and put in refrigerator for about 50 to 60 minutes or until mixture thickens. Stir mixture occasionally during this time. Mixture is ready when it's getting semi-solid but is still soft and pliable.
4. Put chopped peanuts in a shallow dish. Put cocoa powder (if using) in separate shallow dish.
5. Remove chocolate mixture from refrigerator. Scoop mixture out using a tablespoon and form golf ball size balls (or a bit smaller) using the palms of your hand.
6. Roll ball in finely chopped peanuts or cocoa powder and place in candy cups.
7. Return the completed truffles, covered, to the refrigerator until they completely firm up.