Press the Saute button on your Instant Pot and adjust to High.
Add butter. Once melted, add the diced onion and minced garlic. Saute for 5 minutes, stirring occasionally, until softened.
Pour in the chicken broth and scrape any browned bits from the bottom of the pot.
Add the cauliflower florets, seasoned salt, garlic salt, and pepper. Stir to combine.
Secure the lid, ensuring the steam release knob is set to Sealing.
Select the Manual or Pressure Cook button and set the timer for 5 minutes on High Pressure.
Once the timer beeps, carefully move the steam release knob to Venting for a quick release. Remove the lid and stir in the heavy cream.
Blend the soup until smooth and stir in the shredded cheddar cheese until melted.