Add frozen meatballs to the bottom of a 6-quart Instant Pot electric pressure cooker.
Top meatballs with broken spaghetti noodles, spread them out well, otherwise they will stick together while cooking.
Pour in water and broth then top with pasta sauce. Don't stir.
Cook on manual pressure for 9 minutes then quick release.
Remove lid and stir and let sit for a bit to thicken up as it will look soupy at first. Don’t be alarmed! Allow it to sit, with the top off, stirring occasionally and it will slowly begin to thicken.
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Notes
If noodles stick together while cooking, you can easily break them apart with a fork after cooking.
It's really important to allow the spaghetti to thicken after cooking. It will look soupy at first but thickens as it sits so give it time.