Line a 7-inch springform pan and spray with cooking spray.
Combine graham cracker crumbs with sugar and melted butter and press into bottom of springform pan.
Cream together the cream cheese and sugar until smooth. Add the cocoa powder and mix until well combined. Add 2 large eggs and mix well. Finally, add the vanilla extract and sour cream and mix until smooth.
Pour batter into springform pan on top of the graham cracker crust.
Run a fork back and forth through the cheesecake several times to remove air bubbles.
Cover pan with foil.
Pour two cups of water into the inner pot of the Instant Pot.
Make a sling out of aluminum foil to lower the pan into the pressure cooker.
Close the lid of the Instant Pot and set valve to sealing.
Press "Manual" and set time for 35 minutes. When the timer beeps, let pressure release naturally for 12 minutes then turn valve to "venting."
Once pressure has fully released, remove the lid and carefully remove the cheesecake from the Instant Pot. Cool on the counter for one hour, then place, uncovered, in the refrigerator for at least 4 hours.