LINE 8- or 9-inch-square baking dish or pan with wax paper.
MELT morsels in uncovered, microwave-safe on MEDIUM-HIGH (70%) power for 1 minute; STIR. Morsels may retain some of their original shape. If necessary, microwave at additional 10- to 15-second intervals, stirring just until morsels are melted. Stir peanut butter into melted morsels. Stir in peanuts. Spread fudge into prepared baking dish. Refrigerate for at least 1 hour or until set. Lift from pan; remove paper. Cut into pieces. Store in tightly sealed container or resealable plastic bag.
Cut fudge into four squares and then cut each square in 16 pieces (4x4) to create a total of 64 pieces of fudge.