Place water and trivet inside Instant Pot®. Grease a (7-inch) cheesecake pan and set aside.
Place 16 chocolate cookies in a gallon-sized zip-top and seal. Roll with a rolling pin until small crumbs are formed.
Mix crushed cookies and melted butter together.
Press cookie crust into bottom and 1/2 way up sides of greased cheesecake pan. Place pan in freezer while preparing cheesecake batter.
With an electric mixer, cream together cream cheese and brown sugar. Beat until light and fluffy, about 2 minutes.
Mix in 1/4 cup cream, peanut butter, and 1 teaspoon vanilla. Mix an additional 2 minutes.
Add in eggs, one at a time, beat until just combined. Do not over mix.
Fold in 1/2 chopped peanut butter cups.
Pour batter into cheesecake pan.
Create a foil sling and carefully lower pan into Instant Pot®.
Close lid and set pressure release to sealing.
Press manual or pressure cook button and set to 40 minutes.
Allow pressure to naturally release. Remove lid.
Carefully remove pan from Instant Pot® using foil sling.
Place on a cooling rack and let cool to room temperature.
Heat remaining 1/4 cup cream until steaming.
Pour cream over chocolate chips and remaining 1/4 teaspoon vanilla extract and stir. Let sit 5 minutes, until chocolate is melted. Stir until combined.
Pour ganache over cheesecake.
Refrigerate for a minimum of 8 hours.
Top cheesecake with remaining chopped peanut butter cups and serve.
Serve chilled and refrigerate any leftovers.