Prepare the ingredients: Rinse the broccoli and roughly chop it into uniform sized pieces. Chop the onions and garlic. Measure the flour and broth.
Set the Instant pot to the saute setting. Once it's hot, add the olive oil, onions, and garlic. Cook for a few minutes until the garlic and onions begin to soften.
Add the broccoli florets to the instant pot and pour in half of the vegetable broth. Set the pressure to high for one minute; place the cover on the instant pot. Keep in mind will take about 8 to 10 minutes for the instant pot to reach pressure.
Carefully slow release the pressure after 3 to 5 minutes.
Whisk the flour into the remaining broth and gradually stir it into the pot with the cooked broccoli. Stir for a few minutes until the soup starts to thicken. Add the milk and the grated cheese. Stir until the cheese melts.
Adjust the thickness of the soup to your preference.
Notes
Store leftover soup in an airtight container for 3 to 4 days in the refrigerator.Thicken the soup if it's too thin by gradually whisking in more flour.Instead of adding more flour after cooking the soup, add 1/4 cup of leftover potatoes (mashed or baked are a great option for this), or Greek yogurt.