1. Line a 13-in. x 9-in. pan with foil and grease the foil with 1 teaspoon butter; set aside.
2. In a large heavy saucepan, combine the peanut butter, cheese and remaining butter. Cook and stir over medium heat until melted. Remove from the heat. Gradually stir in confectioners' sugar and vanilla until blended (mixture will be thick).
3. Spread into prepared pan. Chill for 2 hours or until firm.
4. Using foil, lift fudge out of pan. Discard foil; cut fudge into 1-in. squares. Store in an airtight container in the refrigerator. Yield: 3 pounds.