Pour the chocolate chips and butter into a microwave safe bowl. Microwave for 1 minute, stir, followed by 1 more minute.
Once smooth and creamy, mix in the powdered sugar.
Add in the eggs and egg yolk, stirring to combine.
Pour in the vanilla and flour, stir well.
Spray 4 glass containers (6 oz Pyrex bowls) with baking spray.
Pour batter halfway up each bowl.
Add a teaspoon of peanut butter to each bowl.
Pour batter on top of the peanut butter, filling each bowl just about to the top.
Pour 1 cup water onto bottom of Instant Pot and place trivet inside.
Stack 3 bowls on bottom of Instant Pot, followed by 1 bowl in center on top.
Place lid securely on top and ensure valve is in sealing position.
Cook manual high pressure for 9 minutes, followed by a quick release.
Remove from Instant Pot and turn each bowl upside down onto a plate.
Serve with ice-cream, caramel, or chocolate sauce on top and enjoy immediately!