In a large mixing bowl, combine all meatball ingredients. Mix well to integrate with hands.
Portion and form meat mixture into balls. (It’s best to keep these meatballs on the smaller side, so they can cook through with less time—I recommend aiming for around 20-24 meatballs, or as many as 32 mini meatballs if you like. I use a cookie scoop to make my portioning easier!)
Pour broth into pressure cooker. Break spaghetti noodles in half, then add to cooker with salt. Stir to submerge noodles.
Add tomato sauce on top, followed by meatballs.
Close the lid and cook on manual setting at high pressure for 5 minutes. (See note below about manual setting on different pressure cookers.)
Turn off heat and flip Quick Pressure Release switch to release steam for 10 minutes.
Carefully open lid—watch out for steam—and transfer meatballs, noodles, and sauce from pressure cooker into a dish or storage container. (When you first open the lid, it will look like there is a lot of liquid—but once you give it a stir, it absorbs and integrates perfectly!)
Serve and enjoy!
Yields ~8 cups cooked spaghetti & ~20-30 meatballs, depending on size (6 servings total).