Turn the Instant Pot to saute and allow to heat for 1-2 minutes. Once heated, add in the ground meat, onion, and garlic. Saute the beef, breaking it up into small pieces as it browns until the meat is fully cooked.
Once the meat is browned, turn the Instant Pot off by hitting cancel. Remove meat from the inner pot, drain off any grease, and reserve the meat for later.
Return the inner pot back to the Instant Pot. Add in ½ cup of broth to the inner pot and scrape up any browned bits from the bottom of the inner pot to prevent a burn warning.
Break the spaghetti noodles in half and add them in crisscrossing layers in the inner pot of the Instant Pot. This is a very important step because if you do not crisscross the noodles, they may clump together.
Pour in the remaining broth and gently submerge the noodles into the stock using a spoon. It is okay if they are not fully submerged, the spaghetti sauce will cover the top of the noodles.
Top the noodles with the reserved meat and the spaghetti sauce.
Place the lid on the pressure cooker and be sure the vent knob is pointed to sealed. Set to cook on High Pressure for 5 minutes by hitting pressure cook or manual and then using the +/- buttons to adjust until the timing reads 5.
Once the cooking time has elapsed, let pressure release for EXACTLY 5 minutes naturally. Then release any remaining pressure by using a wooden spoon to knock the vent knob from sealing to venting, being careful to stand away from any steam that may be released.
Open the Instant Pot and gently toss the noodles and sauce together. Serve with Parmesan Cheese if desired.
If using frozen meat, cook frozen ground beef in the Instant Pot first. Remove cooked beef from Instant Pot once cooked and drain off the liquid from Instant Pot. Proceed with the recipe starting with adding noodles into the pressure cooker.Gluten-Free Instant Pot Spaghetti, I have only had success using the Barilla brand of gluten-free spaghetti. Other varieties give off too much starch as they cook in the pressure cooker and ruin the sauce and taste and at times even cause a burn notice.For Vegan or Vegetarian-Friendly Spaghetti omit the meat or use meatless crumbles.Storing Leftovers: Store for 3-4 days in a sealed container in the refrigerator and can be frozen for 3 months. Determining Cook Time: The cook time is determined by cutting the time indicated on the box of spaghetti and cutting it in half. For most brands, this would be equivalent to 5 minutes. For Homemade Spaghetti Sauce, Mix together 24 ounces crushed tomatoes, 6 ounces tomato paste, 2 teaspoons dried oregano, 2 teaspoons minced garlic, ½ teaspoon dried basil, 1 teaspoon garlic powder, 1 teaspoon onion powder, 1 tablespoon sugar, 1 tablespoon olive oil, ¼ teaspoon crushed red pepper flakes, and ¼ teaspoon kosher salt together until well combined and use in place of jarred sauce. See Instant Pot High Altitude Conversion if cooking 2500+ feet above sea level.