Start by heating up oil on the sauté setting. Add garlic and stir. Add onion powder (or fresh onions) and Italian seasoning. Stir and sauté for 1 minute.
Add ground meat and cook, breaking it apart with a wooden spoon, until browned. Season with salt and pepper. Spoon out and discard any grease (this depends on the type of meat you use).
Add ½ cup of water and scrape any bits from the bottom of the pot. This step is important as it will prevent the dish from burning during pressure cooking.
Grab a handful of spaghetti noodles at a time, break in half and arrange in a criss-cross pattern on top of the meat. Add remaining water to the pot.
Pour diced tomatoes (with liquid) and pasta sauce over noodles. Do your best to keep it in the center, away from the edges of the pot. Close the lid, set the valve to sealing.
Set timer to 7 minutes and make sure the IP is set to cook on HIGH pressure. It will take about 10 minutes for the Instant Pot to come to pressure, then it will start the countdown.
Once the timer is done, wait 1 minute, then switch the valve to venting to release pressure.
Open the lid away from your face, as there will be leftover steam in the pot. The dish will look like it has too much liquid, but all you need to do is stir well several times and let it sit for 5 to 10 minutes before serving. It will thicken up.