Start by lining a 9x9 inch baking pan with parchment paper, leaving some overhang for easy removal later.
In a large mixing bowl, combine 1 cup of creamy peanut butter, 1 cup of salted butter, and 2 teaspoons of vanilla extract. Mix until smooth.
Gradually sift in 3 cups of powdered sugar, mixing continuously until fully incorporated. If too crumbly, add a teaspoon of milk.
Transfer the peanut butter mixture into the prepared baking pan and spread it evenly, pressing down firmly.
In a double boiler or microwave-safe bowl, melt 2 cups of semisweet chocolate chips and 3 tablespoons of butter over low heat until smooth.
Pour the melted chocolate over the peanut butter layer in the pan and spread it evenly.
Place the pan in the refrigerator for about 1-2 hours or until the chocolate is fully set.
Once set, lift the candy out of the pan using the parchment paper overhang and slice it into squares or rectangles.
