1 cup (2 sticks) butter, plus additional butter for greasing pan
1 cup creamy peanut butter
1 teaspoon vanilla extract
3-1/4 cups powdered sugar
Directions
Grease an 8-inch square pan with butter. Line with wax paper; set aside. Place butter and peanut butter in 2-quart microwave-safe bowl. Microwave on HIGH, 1-1/2 minutes until butter is melted and bubbles. Stir, mixing well. Return bowl to microwave. Microwave on HIGH, 1-1/2 additional minutes.
Stir in vanilla extract; mixture will begin to bubble up sides of bowl. Add powdered sugar; stir until thickened and well blended. Spread fudge mixture into prepared pan. Smooth over surface. Place a piece of wax paper over surface of fudge. Refrigerate 1-2 hours or until firm. Cut into squares. Store fudge in airtight container at room temperature.