Preheat oven to 350°F. Line an 8-by-8-inch baking pan with aluminum foil, spray with cooking spray; set aside.
In a large bowl, add the flour, confectioners’ sugar, peanut butter, and cut in the butter using two forks until mixture resembles pea-sized crumbly bits.
Turn mixture out into prepared pan, hard-packing it with your fingertips in an even, smooth, flat layer to form a crust. Bake for 15 to 17 minutes, or just until set.
Remove pan from oven and sprinkle with marshmallows. Return to oven for 3 to 4 minutes or until puffed. Don’t brown.
In a microwave-safe bowl, combine peanut butter chips, corn syrup, butter, and heat on high power to melt, about 2 minutes total.
Add the vanilla, then stir in the Rice Krispies and salted peanuts until well combined.
Turn mixture out on top of the marshmallows, smoothing the top with a spatula.
Cover with foil and refrigerate for at least 2 hours, then slice and serve.