Turn the instant pot to the sauté setting. Add in the butter, onions and celery. Sauté until the onions are soft. Add in the garlic and cook for 1-2 minutes until the garlic is aromatic.
Then stir in the broccoli, chicken broth, salt and pepper.
Place the lid on and set the valve on the lid to the “seal” position. Cook on high pressure for 1 minute.
After the cook time, do a quick release to release the pressure from the instant pot.
Stir together the heavy whipping cream and cornstarch together in a small bowl. Switch the instant pot to the sauté setting and stir in the cream mixture.
Continue to stir until the soup starts to boil and then slowly stir in the cheddar cheese. Continue to heat and stir until all the cheese is incorporated and well combined.
Then turn off the instant pot. Serve warm and enjoy!