Summarize:

Line with parchment paper or a silicone sheet. Gently heat. Stir continuously until the sugar dissolves (about 5 minutes). Bring the mixture to the boil, with the candy thermometer in the mixture as it boils, stirring occasionally. Bring to 100C/215F, then lower the heat to a gentle boil. When the mixture reaches 115C/240F, it is ready to remove from the heat. You can use a wooden spoon to do this or make it easier by using a handheld electric whisk or food processor. Beat for 10 minutes. Beat for another 15 minutes or until the mixture ceases to appear shiny. About an hour after cooling, score the square marks on the surface of the fudge. Once completely cooled and set, either cut or break the fudge into squares. The fudge is now ready to serve or give as a gift. For a gift, line a box or other container with wax paper to prevent sticking and leakage of the fat from the fudge. Store in an airtight container.
Prepare the baking dish or pan. Put the sugar, evaporated milk and double (heavy) cream into the saucepan. Turn the heat up to medium. Boil for another 10 minutes on low heat. Whisk the mixture. Pour in the peanut butter. Let cool slightly. Let cool completely.