Turn the instant pot on the ‘Sauté’ mode on ‘High’. Add the olive oil and let the pot heat up for 2 minutes.
Add the ground beef and onions and cook for 3 to 4 minutes or until the beef is brown and the onions are translucent. Keep stirring and breaking down the beef with the spatula.
Add the garlic, Italian seasoning, salt and pepper and cook for another minute till the raw flavor of the garlic is gone.
Turn the ‘Sauté’ mode off. Add 1½ cup of the broth (save the remaining ½ cup for later) to deglaze. Make sure to scrape off every little bit of meat stuck to the bottom of the pot. This will make sure you don’t get a ‘Burn’ message.
Add the macaroni pasta over the beef mixture and spread it evenly. Do not mix them together. They should be in layers.
Add the jar of marinara sauce over the pasta and spread evenly. Again, do not mix.
Add the remaining broth to the marinara jar and rinse it out and pour it over the sauce.
Do not stir or mix the layers up. (TIP: Keep the meat, pasta and sauce layers separate and don’t mix them together. If the pasta touches the bottom of the pot, it’ll stick to it and give a ‘Burn’ message.)
Put the lid on, making sure that the pressure valve is in the “Sealing” position.
Select the Pressure Cook/Manual mode and set the time to 2 minutes. (Note: It took about 12 minutes for my IP to come to pressure.)
When Instant Pot beeps, immediately turn the pressure valve to “Venting” position to do the quick release. (TIP: Make sure to do the quick release as soon as the timer goes off. If it stays too long, the pasta will overcook and become mushy.)
Open the lid and mix everything together. Don’t worry if it looks too dry! Once you mix everything together, it will be just perfect.
Serve immediately with freshly grated parmesan cheese.
Note 1: It's best to use lean beef for the recipe, as you won’t be able to drain the extra fat. But even with lean beef, this recipe is very flavorful.