Add ground beef and onion to the inner pot of the Instant Pot. Sauté until the beef is completely cooked.
Next top with tomatoes, tomato sauce, chicken stock and ketchup and mustard. The pasta should be covered with liquid.
Put the lid on the pressure cooker and turn the pressure valve to sealed. Set manual high-pressure time for 5 minutes, doing a natural pressure release for 4 minutes before letting the remaining pressure out.
Fold in cheddar cheese until melted. Your cheesy pasta is now ready to enjoy.
Notes
To evenly mix pasta in the Instant Pot, use a silicone spatula or wooden spoon to gently fold and stir the pasta, ensuring that all pieces are submerged in the cooking liquid and preventing clumping or sticking to the bottom of the pot.