Set the Instant Pot to its sauté setting, then add the ground beef, Italian seasoning, salt, onion powder, and garlic powder.
1 pound lean ground beef, 1 teaspoon Italian seasoning, 1 teaspoon kosher salt, 1/2 teaspoon onion powder, 1/2 teaspoon garlic powder
Once the meat has rendered a small amount of fat, stir in the onion. Continue to cook, stirring frequently to break up the meat, until the onion is softened and the meat is fully browned. Turn off the Instant Pot.
1/2 small yellow onion
Break the spaghetti noodles in half and fan them in a criss-cross pattern on top of the meat.
16 ounces (1 pound) uncooked spaghetti
Pour marinara sauce, beef broth, water, and diced tomatoes on top. Gently press the spaghetti down so it is mostly submerged in liquid, but do not stir. (This is important!)
24 ounces marinara sauce, 2 cups beef broth, 1 and 1/2 cups water, 1 (14.5 ounce) can diced tomatoes
Close the lid, seal, and cook on high pressure for 7 minutes.
When the 7 minutes is up, do a quick release of the pressure, remove the lid, and stir very well.
Let the spaghetti sit for 5 minutes on the keep warm setting with the lid open, then sample and season with more salt to taste. Serve with generous amounts of grated Parmesan, basil, and red pepper flakes if desired.
Parmesan, fresh basil, and red pepper flakes