Line a 9x9x2-inch baking pan with foil, extending the foil over the edges of the pan. Butter the foil; set aside.
Butter the sides of a 1-1/2- to 2-quart heavy saucepan. In the saucepan, combine sugar, milk, and butter. Cook and stir over medium-high heat until mixture boils. Reduce heat to medium; continue boiling at a moderate, steady rate for 12 minutes, stirring occasionally.
Remove saucepan from heat. Add peanut butter, marshmallow creme, and vanilla; stir until mixture is combined. Spread fudge evenly in the prepared pan. Let stand until fudge is firm (1 to 2 hours). Use foil to lift fudge out of pan. Place chocolate chips in a microwave-safe bowl. Microwave on 70 percent power (medium) for 1 minute; stir. Microwave on 70 percent power about 1 minute more or until melted, stirring after every 15 seconds. Drizzle chocolate over fudge; sprinkle with peanuts. Cut into squares. Place each piece in a paper candy cup and arrange in 9-inch round foil pans; cover.