Butter a large sheet pan (9 x 13)
Combine the cake mix with the eggs, water, oil, and instant pudding.
Spread into baking dish and cook for 30-40 mins at 350 degrees. Set aside to cool.
In a large mixing bowl combine peanut butter, sugar and butter.
Once the sheet cake is cool, spread the peanut butter mixture over the top by dropping large spoonfuls all around, making it easier to spread evenly.
Combine chocolate chips and heavy cream on medium heat in a saucepan. Cook, stirring constantly until the cream and chocolate are well combined.
Pour chocolate ganache (chips & cream mixture) over the peanut butter later.
Top with mini chocolate peanut butter cups.
Set in refrigerator to set for 20 mins or more and serve.