In a large mixing bowl, combine the ground beef, breadcrumbs, grated Parmesan cheese, egg, minced garlic, salt, black pepper, and chopped parsley. Mix until all ingredients are well combined.
Using your hands, form the mixture into meatballs about 1 to 1.5 inches in diameter.
Turn your Instant Pot to the sauté function and brown the meatballs on all sides for about 3-4 minutes.
Once browned, pour in the beef broth and scrape up any browned bits from the bottom of the pot.
Close the lid of the Instant Pot, set the valve to sealing, and cook on high pressure for 8 minutes. Allow the pressure to release naturally for 5 minutes before a quick release.
After removing the lid, carefully add the marinara sauce to the pot and stir to coat the meatballs.
Serve immediately or simmer in the sauce for a few minutes to enhance the flavors.
