Set instant pot to the sauté setting. When hot, add the oil. Then, add the ground beef. Cook, breaking up the meat and stirring occasionally, for about 5 minutes. Drain off any excess grease.
Add onion, bell pepper, garlic, chili powder, salt, and pepper. Cook for another 4 minutes, or until the onions and pepper soften.
Stir in the tomato paste, Worcestershire sauce, and beef broth, making sure to scrape up the bits at the bottom of the pot so you don’t get the burn warning.
Pour in the macaroni and stir. Cover with the lid. Set the valve to the 'sealing' position and pressure cook on high for 5 minutes.
Once the cook time has finished, do a quick release and open the lid. Carefully stir in the cheddar cheese until melted.
Serve hamburger helper hot garnished with chopped parsley on top, if desired.
