- In a large bowl, combine softened butter, peanut butter, powdered sugar, and vanilla extract. Beat with an electric mixer until smooth and thick.
The dough will be crumbly.
- Line a 9×13-inch pan with parchment paper. Press the peanut butter dough firmly into the dish.
- In a microwave-safe bowl, melt chocolate chips and butter in 30-second intervals, stirring until smooth.
- Pour the melted chocolate over the bars, spreading evenly. Let it set at room temperature for 30-60 minutes.
- Remove the bars from the pan using the parchment paper, transfer to a cutting board, and slice with a sharp knife.
- Refrigerate for at least 1 hour before serving.