Grease 9 x 13 inch pan with non stick cooking spray.
In a large bowl, combine melted butter, salt, cocoa and vanilla.
Stir in the sugar and eggs.
Add in the flour and peanut butter and mix until smooth.
Pour into prepared pan and bake for 22-25 minutes.
Remove from oven and let cool.
While the brownies cool, prepare frosting by beating butter, whipping cream, water, and cream cheese in a bowl on medium speed until fluffy.
Gradually beat in cocoa and powdered sugar until smooth. Spread over cooled brownies.
Sprinkle peanuts, peanut butter cups, and peanut butter chips on top of the frosting.
Cut into squares and serve.
Notes
These brownies do freeze quite well. They are better fresh, but I have frozen them, and they thaw nicely. We recommend freezing them in an airtight container.