1. Line an 8-inch square pan with foil; butter foil. Combine marshmallow cream, sugar, evaporated milk and butter in a large, heavy pan. Bring mixture to a boil over medium-high heat. Cook, stirring constantly, until mixture reaches 235°F on a candy thermometer, 10 to 15 minutes.
2. Remove from heat and stir in candy corn, chocolate chips and peanuts, stirring until chocolate melts. Immediately transfer to foil-lined pan and smooth top until even. Chill until set, at least 2 hours.
3. In separate bowls over pans of simmering water, melt semisweet and white chocolate, if desired. Using forks, drizzle both chocolates over fudge. Cut fudge into squares.