Set the Instant Pot to Sauté (Normal/Medium). Add the olive oil and let it heat for 1–2 minutes. Add the ground beef and chopped onion. Cook, breaking up the beef with a wooden spoon, for about 5–7 minutes, until the beef is mostly browned and the onion is softened.
1 tablespoon olive oil, 1 pound ground beef, 1 small yellow onion
Stir in the minced garlic, salt, black pepper, Italian seasoning, smoked paprika, and red pepper flakes. Cook for about 1 minute, just until fragrant, stirring constantly so the garlic does not burn.
3 cloves garlic, 1 teaspoon kosher salt, 1/2 teaspoon black pepper, 1 teaspoon dried Italian seasoning, 1/2 teaspoon smoked paprika, 1/4 teaspoon crushed red pepper flakes
If there is a lot of grease in the pot, carefully tilt the pot and spoon off some of the excess fat. Pour in 1/2 cup of the beef broth and scrape up any browned bits from the bottom of the pot to help prevent a Burn warning.
2 cups low-sodium beef broth
Turn off Sauté. Add the dry pasta on top of the meat mixture and spread it out gently without stirring. In a small bowl, whisk the remaining 1 1/2 cups beef broth with the tomato paste and Worcestershire sauce, then pour over the pasta. Pour the jar of marinara or pasta sauce over everything. Do not stir; keep the layers as they are.
2 cups low-sodium beef broth, 24 ounces marinara or pasta sauce, 8 ounces short pasta, 1 tablespoon tomato paste, 1 teaspoon Worcestershire sauce
Lock the lid and set the valve to Sealing if needed. Cook on Manual/Pressure Cook (High Pressure) for 5 minutes. When the cooking time is up, allow a 5-minute natural release, then carefully perform a quick release for any remaining pressure.
Open the lid away from your face. The mixture may look loose at first. Stir well, combining the pasta and beef evenly. Taste a piece of pasta; if it is slightly too firm, turn on Sauté (Low) and cook, stirring, for another 1–3 minutes until the pasta is just tender.
Turn off Sauté. Stir in the shredded cheddar cheese, Parmesan, and heavy cream or half-and-half (if using) until the cheeses are melted and the sauce is creamy. If the mixture looks too thick, add a tablespoon or two of warm water or broth; if too thin, let it sit a few minutes so the pasta can absorb more liquid.
1 cup shredded cheddar cheese, 1/4 cup grated Parmesan cheese, 1/4 cup heavy cream or half-and-half
Sprinkle with chopped parsley or basil, if desired. Serve hot straight from the Instant Pot, with a salad or steamed vegetables on the side.
fresh parsley or basil