• Put the whole Oreos into food processor until they are crumbs. Transfer to bowl and mix in the melted butter.
• Grease a 7 inch springform pan and place a circle of parchment paper in the bottom. Dump the crust mixture into the pan and press down into an even layer. Chill in freezer for at least 10 minutes while you prepare the filling.
• Beat the cream cheese and sugar until light and fluffy. Add the yogurt/sour cream and the Baileys, and beat until thoroughly combined. Mix in the vanilla extract, followed by the eggs, one at a time.
• Transfer filling to chilled crust and tap the pan on the counter to bring any air bubbles to the surface, and pop with a fork or toothpick. Cover with aluminum foil.
• Put 1 1/2 cups of water in the Instant Pot. Place a trivet in the bottom, and carefully lower the cheesecake into the pot, either with the trivet handles or a silicone bakeware sling.
• Put the lid on the Instant Pot, turn the knob to Sealing, and set to High Pressure for 40 minutes.
• When the time is up, allow to naturally pressure release for 10 minutes before venting. Allow cheesecake to cool at room temperature for an hour, then run a sharp knife around the edge of the pan. Refrigerate for a minimum of 4 hours.

For the Ganache

• Combine chocolate chips and cream in a microwave safe bowl (or can use double boiler method). Microwave for 25 seconds. Whisk for one minute, or until all the chocolate is melted. If all the chocolate is not melted, microwave for another 10 seconds and whisk again.
• Pour over chilled cheesecake, and return to the refrigerator to set the ganache. Dust with cocoa powder, if desired.