| 1 | Butter an 8-inch-square baking pan. |
| 2 | Line the bottom of the pan with foil. |
| 3 | In a large bowl, combine the butter, chocolate chips, macadamia nuts, unsweetened chocolate, and vanilla. |
| 4 | Attach a candy thermometer to a medium saucepan. |
| 5 | Add the sugar, evaporated milk, and marshmallows. |
| 6 | Bring to a boil over medium heat, stirring constantly to prevent burning. |
| 7 | Cook, stirring constantly, until the mixture reaches 238 degrees. |
| 8 | Pour the hot mixture into the bowl and let stand for 30 minutes. |
| 9 | Stir until the mixture begins to thicken, about 1 minute. |
| 10 | Spread evenly in the prepared pan. |
| 11 | Let stand until completely cooled. |
| 12 | Cover with foil and let stand overnight to allow the flavors to mellow. |
| 13 | Invert the fudge and remove the foil. |
| 14 | Reinvert and cut into squares. |
| 15 | Store the fudge at room temperature in an airtight container. |
| 16 | Makes about 2 pounds. |
