Line a 9x13-inch baking dish with parchment paper, allowing some overhang for easy removal later.
In a mixing bowl, combine the softened unsalted butter, creamy peanut butter, all-purpose flour, and confectioners' sugar. Mix until smooth.
Fold in the marshmallows gently into the mixture, ensuring they are evenly distributed.
Spread the peanut butter mixture evenly into the prepared baking dish. Press it down firmly.
In a small saucepan over medium heat, combine the light-colored corn syrup and 2 tablespoons of unsalted butter. Stir until melted. Remove from heat and stir in vanilla extract and peanut butter chips until smooth.
In a large bowl, combine the Rice Krispies and salted peanuts. Pour the melted peanut butter mixture over them, stirring gently until fully coated.
Pour the Rice Krispie mixture over the peanut butter base in the baking dish. Press down evenly.
Allow the bars to cool at room temperature for about an hour, then refrigerate for at least 2 hours to set completely.
Once set, lift the bars out using the parchment paper overhang. Cut into squares and enjoy!