Set your Instant Pot to the sauté function over medium heat. Once hot, add the lean ground beef and cook for 5–7 minutes, breaking it apart with a wooden spoon until browned and no longer pink. Drain any excess fat, then remove the beef and set aside, leaving any flavorful bits in the pot.

In the same pot, add the diced yellow onion. Sauté for 3–4 minutes, stirring frequently, until the onions are softened and slightly translucent.

Add the minced garlic, dried Italian seasoning, salt, black pepper, and crushed red pepper to the pot. Stir and cook for about 30 seconds until the garlic becomes fragrant.

Pour in ½ cup of reduced-sodium beef broth, using a wooden spoon to scrape the browned bits from the bottom of the pot. Allow the mixture to simmer for a minute.

Add the uncooked shell pasta, crushed tomatoes, and the remaining beef broth to the pot. Carefully push the pasta down into the sauce without stirring.

Seal the Instant Pot lid securely and set it to manual high pressure for 4 minutes.

After 4 minutes, carefully turn the pressure release valve to venting to release the steam.

Once the pressure is fully released, open the lid and stir in the heavy cream and half of the grated cheddar cheese.

Top with the remaining cheese, allowing it to melt before serving.