Add the olive oil to an 8 quart instant pot and press the sauté function. When it is hot, add in your onion and ground beef. Sauté until your beef is no longer pink.
Add in the celery, carrots, dried basil, dried parsley, and italian seasoning and cook for 5 minutes.
Add in the potatoes and broth. Put on the lid and lock into place.
Make sure the instant pot vent is set to "sealing" and select "high" on the "pressure cook/manual" setting. Put the cooking time to 3 minutes.
Once done, let the pressure release naturally for about 10 minutes and then release the rest of the pressure with the pressure valve (known as a quick release). Be sure to cover the valve with a towel to prevent the steam from burning you- it is very hot.
In a small saucepan on the stove, melt the butter while the pressure on your instant pot releases.
Add in the ¼ cup flour and whisk to combine. Slowly add in the milk and whisk to make a roux.
Add the roux to the soup and stir to thicken.
Add the shredded cheese and stir until melted. If the cheese doesn’t melt, press the sauté button and let it heat up the soup to melt the cheese. Turn it off once the soup is heated.
Stir in the salt, pepper, and sour cream and enjoy!