Add butter and onion to the instant pot and saute until butter is melted and cooking onions until tender. Add broth, soup, spices and frozen hash browns and stir well.
Place the lid on the electric pressure cooker and seal shut. Set to manual, low pressure for 3 minutes. (or high for 2 minutes if you don't have low)
When cooking is complete, let pressure release naturally for 10 minutes. Open the pot and stir in 1 cup of cheddar cheese and cream cheese. Mix until completely melted. Serve topped with remaining shredded cheese if desired.