Put 1 cup water in the Instant Pot and put the trivet at the bottom
In a food processor, pulse cookies until cookies are fine crumbs
Stir melted butter into crumbs and press into bottom and lower sides of pan
Place pan and crust into freezer while making filling
In a mixer fitted with the paddle attachment, beat cream cheese and sugar until smooth
Blend in peanut butter, vanilla extract, and flour, and beat
Mix in eggs and yolk one at a time until just blended, don't over mix
Stir in chocolate chips
Pour batter into prepared crust, then cover pan with foil
Lay a paper towel on top of aluminum foil and wrap the bottom of the springform pan. Make a sling out of foil.
Place pan in sling into IP on trivet. Lock lid and set IP to Sealing.
Select Manual High Pressure for 55 minutes - 10 minute natural release.
Remove and cool cheesecake when finished - refrigerate overnight.
Prepare the chocolate topping by melting the chocolate chips and butter in the microwave for one minute. Stir. Microwave in 15 second segments until totally melted. Stirring each time. Stir in the milk and corn syrup until smooth. Pour the mixture over the top of the cheesecake and spread with a spatula over the top and the sides of the cake. Top with chopped Reese cups.