Line an 8x8-inch square baking pan with parchment paper or foil, and set aside.
Add the marshmallows to a large microwave-safe bowl and heat in 30 second intervals, stirring after each one, until completely melted.
Add the melted butter, peanut butter, and vanilla, and whisk until combined.
Add the Rice Krispies and mix until completely coated.
Spoon the mixture into the prepared pan and spread out. Press firmly into a packed, even layer.
For the Topping
Add the chocolate and peanut butter to a microwave-safe bowl and heat in 30 second intervals, stirring after each one, until melted and smooth.
Pour the chocolate over the Rice Krispie layer and spread out evenly.
Refrigerate until set - about 30 minutes. Cut into squares, serve and enjoy!
Video
Notes
This recipe can easily be doubled to fit a 9x13-inch pan.Leftovers can be stored in an airtight container at room temperature for up to 3 days. They also freeze well, wrapped individually, for up to 2 months. Thaw overnight at room temperature.