Press the sauté button on the Instant Pot, allow it to heat up for 2 minutes and then add the onion, garlic, carrot, broccoli (stems and florets), salt and thyme. Cook for 3 minutes, stirring frequently so nothing sticks to the bottom of the pot.
Turn off the Instant Pot, add the water and stir. Lock the lid into place, making sure the nozzle is in the sealing position.
Use the manual mode and set the timer for 4 minutes. When the timer goes off, use the quick release method.
When the pressure is totally down, take off the lid and remove about half of the broccoli florets and place them in a bowl. You don’t have to take your time with this. Use a slotted spoon and just fish a few spoonfuls out. No biggie if you pick up other veggies with your spoon along the way.
Now add the white beans and the nutritional yeast (if using) to the Instant Pot and allow to cool for about 10 minutes. Stirring the soup will help it cool faster.
When it’s cool, blend the soup (minus the broccoli florets that you just reserved) in batches in your blender (or all in one go with a blender stick), until all of the soup is creamy and smooth.
When all of the soup is blended, add the reserved broccoli florets back into the pot, along with the parsley, black pepper and a little more salt to taste (if needed). Stir and let cool completely before you place in a container and store in the fridge.