Place room temperature butter in large mixing bowl, along with sugar. Mix until fully combined. Add eggs and blend until fully incorporated. Add vanilla extract and mix again.
In a separate mixing bowl, add all dry ingredients: flour, cocoa powder, baking powder, and salt. Whisk together until combined.
Pour wet ingredients into bowl with dry ingredients, or vice versa. Gently mix until fully combined. Then, using a rubber spatula, add chocolate chips to batter and mix again.
In a small bowl… add cream cheese and milk. Whisk together until smooth and creamy. Add cream cheese mixture to piping bag (or ziplock bag) and cut off a very small corner.
Spray a 7×3 push pan with nonstick cooking spray. Pour batter into pan and spread out evenly.
Starting in the center of the brownie batter… gently squeeze the piping while rotating the pan to make a swirl all the way out to the edges. Then, using a toothpick (or knife), draw lines in the batter, from center to edges, to make the cream cheese look like a spider web.
Cover pan with aluminum foil. Add a 3-inch trivet and 1 1/2 cups of water to cooker. Place push pan on top of trivet. Lock lid and cook for 70 minutes at high pressure. Once cook time is complete, allow pressure to release naturally for 10 minutes. Then quick-release remaining pressure.
Remove pan from cooker and uncover, but allow brownies to cool in the pan for about 10 minutes before removing.