- 1 cup butter, softened
- 1/2 cup creamy peanut butter, or more to taste
- 1 teaspoon vanilla extract
- 1 pinch salt
- 4 cups confectioners' sugar
- 1/4 cup milk, or more as needed
- Beat butter in a bowl using an electric mixer until fluffy. Add peanut butter, vanilla extract, and salt; beat until incorporated. Slowly pour confectioners' sugar into peanut butter mixture while continuing to beat with the mixer; add milk until desired thickness is reached.