Turn your Instant Pot/Multi-Cooker on to Sauté. Add oil, onion, and carrot. Cook, stirring occasionally, for 2 to 3 minutes or until the onion starts to get golden brown around the edges.
Add ground meat, sprinkle with 1/2 tsp salt, and then the balsamic vinegar. Stir and scrape up any bits stuck to the bottom of the pot. (The meat may not be fully cooked at this point... that’s ok.) Add the marinara, broth, and frozen spinach. Stir to combine.
Place the lid on your pressure cooker, set on Manual high pressure for 10 minutes, and make sure the top valve is sealed.
Once time is up, release the pressure and remove the lid. Stir in broken lasagna noodles. Place top back on the pot, seal the valve, and set to Manual high pressure for 3 minutes.
Release the pressure immediately, remove the lid, then stir in the Parmesan cheese. Taste for seasoning and add salt and pepper as needed. Serve warm with shredded cheese or ricotta on top.