In a medium sized mixing bowl, combine the heavy whipping cream and sugar. Using a mixer, beat the cream until stiff peaks form, about 2 minutes. It should look smooth and not grainy.
Add the vanilla Greek yogurt into the whipped cream and gently fold it in until just combined. Be sure not to over-mix.
Place the peanut butter in a microwave safe dish and heat in the microwave in 30 second increments until the peanut butter has become loose. It should easily be able to run off of a spoon.
Begin to assemble the parfait by taking two 12-ounce glasses and adding a layer of chopped brownie to the bottom.
Next add about one tablespoon of peanut butter over the brownie layer. Then add a layer of the cream. Repeat this process one more time starting with the brownie layer.
Top the final cream layer with some chopped peanut butter cups and enjoy!