Spray a 9x13 baking dish with non stick cooking spray.
In a large microwave safe bowl, heat marshmallows, peanut butter, chocolate chips and butter on high in microwave for one minute.
Stir ingredients and microwave for another 30 seconds.
Once ingredients start to melt, stir in cereal, peanuts and salt.
Transfer mixture to baking dish and set aside to cool.
Prepare frosting by melting chocolate chips, butter and milk in a medium sized microwavable bowl, in microwave on high for one minute.
Stir together until smooth and transfer to bowl of a stand mixer.
Using a paddle attachment, beat in two cups of powdered sugar.
Add vanilla extract,
Top fudge mixture with frosting and sprinkle with additional Peanut Butter and Cocoa Pebbles, peanuts and chocolate chips. Press gently into frosting.
Refrigerate for at least two hours before cutting and serving.