1 cup unsalted butter, plus more for greasing pan
1 cup peanut butter (use Peter Pan, it gets the best results in baking)
1 teaspoon vanilla
1 pound powdered sugar
Microwave butter and peanut butter for 2 minutes. Stir and microwave for 2 more minutes. Add vanilla and powdered sugar to peanut butter mixture and stir to combine. Pour into a buttered 8 by 8-inch pan lined with waxed paper. Place a second piece of waxed paper on the surface of the fudge and refrigerate until cool. Cut into 1-inch squares and store in an airtight container.