Place butter in large mixing bowl. Using a hand mixer, mix butter just a few seconds to get it going. Then add sugar and continue mixing 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 dry ingredients into bowl with wet ingredients. Gently mix until fully combined. Add chocolate chips to batter. Then, using a rubber spatula, mix well.
Spray a 7×3 push pan with nonstick cooking spray. Pour batter into pan and spread out evenly.
Add a 3-inch trivet and 1 1/2 cups of water to cooker. Place push pan on top of trivet. Cover pan with aluminum foil. This will keep out moisture.
Lock lid and cook for 50 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, but allow brownies to cool in the pan for about 10 minutes before removing.
Serve warm with vanilla ice cream!