Wrap the bottom of a 7" springform pan with aluminum foil. Be sure it's a single layer and avoid bunching the foil around the sides. Set aside.
Begin by crushing Reese's Puffs cereal in a food processor or blender to make Reese's flour. Mix this with the cocoa and peanut butter powders. Combine remaining liquid crust ingredients and stir until you have a dough-like mixture.
Add the crust mixture to the springform pan. Using a rubber spatula or nonstick utensil, spread the crust out evenly across the bottom of the pan. Once you've made your crust, place it in the freezer while you make the cheesecake.
For the cheesecake, whisk the cream cheese and Greek yogurt together in a large bowl. (You can also use a hand mixer for this step.) Add the eggs in gradually, stirring in one at a time. Finally, add the protein powder and any sweetener should you need it.
Remove your crust from the freezer and add the cheesecake mixture on top. It should spread on its own, but you can use a spatula or spoon to ensure it's evenly distributed.
Cover the top of your cheesecake with foil. Again, be sure to not bunch the foil but cover fully.
Fold another long piece (~2 feet) of foil into a long rectangle or roll it up longways like a scroll, if that helps give a visual. You'll use this as a handle to easily remove the springform pan from the Instant Pot.
Add 1 C water to the bottom of the Instant Pot and insert rack. Place your "scroll" in the bottom of the Instant Pot on top of the rack, sides sticking out of the Instant Pot. Last but not least, insert the springform pan and cheesecake into the Instant Pot. Fold the ends of the "scroll" down before shutting the lid.
Cook the cheesecake on manual for 35 minutes with a 10-minute natural release.
Release the remaining pressure and remove your cheesecake using your handy dandy scroll handles. Be careful, as the handles, pan, and pot will all still be hot.
The center of your cheesecake should be a bit jiggly but not runny. If this is your first cheesecake, don't worry, it will finish cooking after removing it from the Instant Pot. Be sure to cover again after checking on it.
Set the cheesecake on a wire rack or on a safe surface to cool to room temp. Once your cheesecake has cooled, place it in the refrigerator for 4+ hours minimum before releasing the springform pan. (Use a knife to separate sides from pan before releasing if needed.)
Add your desired toppings, slice into 8 pieces, and store in the refrigerator for up to 4-5 days.
For the topping, heat evaporated milk and chocolate chips in the microwave for 10-15 seconds until you can fully mix the chocolate chips into the milk. Allow the mixture 30-60 seconds to cool before adding the cocoa and protein powder. Stir well and add to the top of the cheesecake once it's cooled. Top with Reese's Puffs cereal when you're ready to eat a slice as the Puffs will get stale in the refrigerator.