Turn the Instant Pot to Sauté and heat 1 tablespoon olive oil until shimmering. Add 3 garlic cloves (finely chopped), 1 teaspoon onion powder, and 2 teaspoons Italian seasoning; sauté, stirring, for about 1 minute.

Add 1 lb ground beef and break it apart with a spoon. Cook until browned, then season with 1 teaspoon salt and ¼ teaspoon black pepper. Spoon out and discard excess grease if desired.

Pour ½ cup of the 3 ½ cups water into the pot and scrape the bottom to loosen any browned bits.

Break 12 oz spaghetti noodles in half. Grab handfuls and arrange the broken noodles in a criss-cross pattern on top of the meat.

Add the remaining 3 cups water over the noodles.

Pour the 15 oz can diced tomatoes (with their liquid) and the 24 oz crushed tomatoes or pasta sauce over the noodles, aiming to keep most of the tomatoes toward the center and away from the pot edges.

Close the lid and set the valve to Sealing. Select Pressure Cook/Manual on HIGH and set the cook time to 7 minutes. (The Instant Pot will take about 10 minutes to come to pressure before the countdown starts.)

When the cook time ends, wait 1 minute, then carefully switch the valve to Venting to quick-release the remaining pressure. Wait until the float valve drops.

Open the lid away from your face. Stir the pasta well several times to combine; it will look loose at first. Let it sit for 5–10 minutes to thicken before serving.