- 8 ounces unsalted butter, plus more for greasing pan
- 10.5oz smooth peanut butter
- 1 teaspoon vanilla extract
- 12 oz powdered sugar
- Combine the butter and peanut butter in a 4-quart microwave-safe bowl and cover with plastic wrap. Microwave for 2 minutes on high. Stir and microwave on high for 2 more minutes. (Use caution when removing this mixture from the microwave, it will be very hot.)
- Add the vanilla and powdered sugar to the peanut butter mixture and stir to combine with a wooden spoon. The mixture will become hard to stir and lose its sheen.
- Spread into a buttered 8 by 8-inch pan lined with parchment paper. Fold the excess parchment paper so it covers the surface of the fudge and refrigerate until cool, about 2 hours.
- Cut into 1-inch pieces and store in an airtight container at room temperature for up to a week.