Step One: Prepare the Pan
Spray the 8-inch baking pan with cooking spray. Line the bottom and two of the sides with parchment paper, leaving a two-inch overhang.
Step Two: Combine Butter, Peanut Butter, and Vanilla.
Melt one stick (8 tablespoons) of butter. Mix butter in a large bowl with 1 ½ cups of peanut butter and vanilla. Mix until fully combined.
Step Three: Add in Confectioners’ Sugar
Stir the confectioners’ sugar into the mix, adding ½ cup at a time. Mix until fully combined.
Step Four: Add Peanut Butter Mixture to Pan
Using your hands, transfer the peanut butter to the pan. Press it flat to smooth out the top.
Step Five: Combine Chocolate and Butter
Combine four tablespoons of butter and chocolate in a metal or heatproof bowl. Set the bowl over a saucepan with two inches of simmering water. Stir with a rubber spatula until fully melted.
Step Six: Pour Chocolate onto Peanut Butter Bars
Remove the chocolate from the heat and allow it to cool for about three minutes, stirring regularly. Pour the chocolate over the peanut butter bars, tilting the pan to ensure the chocolate is evenly spread.
Step Seven: Combine Remaining Butter and Peanut Butter
In a small bowl, combine two tablespoons of melted butter with ¼ cup peanut butter until smooth. Let stand for around five minutes, to allow the mixture to thicken up. Gently pour the mixture on the bars, a small amount at a time, and use a toothpick or wooden skewer to create designs.
Step Eight: Refrigerate Bars
Refrigerate bars for at least four hours or until firm. Cut bars into two-inch squares and serve cold.
These peanut butter bars are so tasty and easy to make, it will be hard to keep your hands off them. When you are ready to serve them, run a paring knife along the edges without parchment paper. Use the parchment that overhangs to lift the bars out of the pan and then cut them into two-inch squares.