01 -
Preheat the oven to 175°C (350°F). Grease a 9x13-inch pan with nonstick cooking spray and set aside.
02 -
In a large bowl, mix the melted butter, brown sugar, and granulated sugar using a hand mixer until blended. Add eggs and vanilla extract and mix until fully incorporated. Then mix in the peanut butter until smooth.
03 -
In a separate bowl, whisk together the salt and flour. Slowly add the dry mixture to the wet mixture and mix until just combined.
04 -
Spread the batter evenly into the prepared pan. Bake for 25–30 minutes, or until golden and a toothpick inserted in the center comes out clean. Let the bars cool completely after removing them from the oven.
05 -
In a large bowl, beat the softened butter and marshmallow fluff together. Gradually add powdered sugar, one cup at a time, until blended and smooth.
06 -
Spread the frosting evenly over the cooled bars and sprinkle chopped peanuts on top. Cut into portions and serve.