Prepare the Batter: In a microwave-safe bowl, melt the sugar, butter, and peanut butter by microwaving for 90 seconds. Stir in vegetable oil until smooth. Whisk in cocoa powder, water, and vanilla extract. Add eggs and whisk until combined. Mix in the flour, baking powder, and salt. Stir in the peanut butter and chocolate chips.
Prepare the Pan: Generously spray a 7 x 3-inch springform pan with nonstick cooking spray. Line the bottom with parchment paper and spray it as well.
Assemble the Tart: Pour the prepared batter into the pan and use a spatula to smooth the top. Evenly distribute the cookie dough balls on the surface, gently pressing them in while keeping them visible.
Set Up the Instant Pot: Pour 2 cups of water into the Instant Pot. Place the springform pan on the trivet and lower it into the Instant Pot using the handles. There’s no need to cover with foil.
Pressure Cook: Secure the Instant Pot lid and set the valve to sealing. Select Manual/Pressure Cook on High Pressure for 25 minutes. Allow a 5-minute natural release, then quickly release the remaining pressure.
Cool & Serve: Carefully remove the pan from the Instant Pot and place it on a trivet or cooling rack. Let it cool for 1 hour before serving. Run a knife along the edges before unlatching the springform pan. If you prefer a fudgier texture, chill in the fridge for 2-3 hours before serving.