Hit the sauté function on the Instant Pot. Add in a bit of oil and let heat for 30-60 seconds. Once heated, add in the ground beef and minced onion. Sauté the beef and onion together, breaking up the meat into small pieces as it browns. Once almost fully browned, add in the minced garlic and continue to cook for 1 minute to finish cooking the beef and lightly toast the garlic.
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 layer them inside the inner pot in a criss-crossing fashion, to prevent the noodles from clumping together.
Pour the remaining 3½ cups of broth over the noodles. Gently submerge the noodles into the liquid using a spoon as best you can. It is okay if they are not fully submerged. Top the noodles with the browned meat mixture meat and the prepared 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.
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Notes
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.Meatless Spaghetti: Omit the meat, onions, and garlic and begin the recipe by layering the spaghetti. Be sure to still use 4 cups of liquid. Storing Leftovers: Store leftover spaghetti in an airtight container for up to 4 days in the refrigerator. Alternatively, freeze for up to 3 months. Defrost in fridge if needed, and reheat individual servings in a heat-safe bowl covered with a damp paper towel in the microwave in 30-second intervals until warmed through. 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.