Preheat oven to 350 degrees. Prepare brownie mix according to box.
Muffin Pan: Grease two muffin pans (12 muffins each pan!). Put about 2 scoops of brownie batter in each muffin cup. You only want to fill 1/3 of the muffin cup. Cook brownie for 13-15 minutes at 350 degrees. -OR- 13x9 Pan: Pour all the brownie batter into a greased 13x9 pan and cook for 25-28 minutes at 350 degrees.
Remove brownies from oven and cool completely.
Remove the ice cream from the freezer and let sit out on the counter while you make the peanut butter sauce and chocolate ganache.
Prepare the peanut butter sauce. Heat 1/2 cup whipping cream in a small saucepan on medium heat until it starts to boil. Remove from heat and pour over 1 cup peanut butter chips in a small bowl. Let sit for 1 minute. Stir peanut butter chips and cream until all the chips are melted and you have a creamy mixture. Set aside.
Prepare the chocolate ganache. Heat the second 1/2 cup whipping cream in a small saucepan on medium heat until it starts to boil. Remove from heat and pour over 1 cup semi-sweet chocolate chips in a small bowl. Let sit for 1 minute. Stir chocolate chips and cream until all the chips are melted and you have a creamy ganache mixture.
When brownies are completely cool - carefully spread softened vanilla ice cream over the brownies.
Immediately pour the sauces on top of the ice cream.
Muffin Pan: Pour 1 TBSP of peanut butter sauce on top of each dessert. Then pour 1 TBSP of chocolate ganache on top of the peanut butter sauce. Sprinkle with chopped peanut butter cups.-OR-13x9 Pan: Pour all the peanut butter sauce evenly over the ice cream layer. Then pour all the chocolate ganache evenly over the peanut butter layer. Sprinkle with chopped peanut butter cups.
Put in freezer for 2-3 hours (muffin pans) or 6-8 hours (13x9 pan). Serve and enjoy.