1cupunsalted butter, plus additional for greasing pan
1cupcreamy peanut butter
1teaspoonpure vanilla extract
1lbpowdered sugar(or about 3 ¾ cups), unsifted
Instructions
Butter the bottom and sides of an 8- x 8-inch pan, and then line the bottom and sides of the pan with a sheet of parchment paper. (The butter helps the paper stick to the pan.) Lightly butter the top of the parchment paper, as well.
Combine the 1 cup butter and peanut butter in a large microwave safe bowl, cover with plastic wrap and microwave on full power for 2 minutes. Carefully remove the bowl from the microwave, uncover and stir with a rubber spatula or wooden spoon. Recover and microwave on full power for an additional 2 minutes.
Remove the bowl from the microwave. Carefully stir in the vanilla and powdered sugar until evenly combined. The mixture may become a little crumbly at first, but continue to stir until the ingredients are smooth and a nice "dough" forms.
Pour the mixture into the prepared pan and spread into an even layer, pushing to fill the corners. Place an additional square piece of parchment paper directly on the surface of the fudge and use your hands to smooth the top.
Refrigerate at least 2 hours. Once chilled, transfer fudge to a cutting board by lifting the sides of the parchment paper. Use a large knife to cut into 1-inch cubes.
Store in an airtight container at room temperature for up to 1 week.
Notes
Be careful when measuring the powdered sugar. 1 lb (or 16 oz) of powdered sugar is equal to 3 ¾ to 4 cups. Do not think in terms of liquid measurement where 16 ounces equals only 2 cups.