Ingredients
2 boxes brownie mix (water, oil and eggs per box instructions)
1- 18oz jar crunchy peanut Butter
Directions
Bake 2 packages of brownies in a 15" x 10" jelly roll pan as directed on the brownie mix package (for most packages--350 degrees F. for approx. 20-25 minutes). While the brownies are still warm, spread 1-18 oz jar of chunky peanut butter on top of them. Tip: The peanut butter spreads easier if you microwave it for 2 minutes at 50% power. Give it a vigorous stir and then spread it on top of the brownies. Chill the peanut butter covered brownies in the refrigerator for 30 minutes.
Chocolate Frosting
1/2 cup butter
1/3 cup milk
10 large marshmallows
1/4 cup cocoa
1 package powdered sugar (16 oz) or approx. 3 1/2 to 4 cups
Directions
In a large saucepan, cook the butter, milk and marshmallows over medium heat until they are all melted together. Remove from heat and whisk in the cocoa powder. Mix in powdered sugar with a handmixer a little at a time until the frosting is smooth and has a spreadable consistency. Immediately spread chocolate over the cooled peanut butter layer. Place pan back in the refrigerator and cool an additional 20 minutes before cutting into squares.
Source: Squidoo
From: http://mybiscuitsareburning.blogspot.com/2012/06/peanut-butter-frosted-brownies.html