Place the butter in a 6-8 quart Instant Pot and use the “Saute” function to melt the butter.
Add the red onion and jalapeno peppers and cook for 2-3 minutes or until tender.
Add the entire can of tomatoes with chiles (including the juice) to the Instant Pot, then place the cream cheese and seasonings on top.
Place the lid on the Instant Pot, move the valve to the “sealing” position, and set Pressure Cook for 1 minute.
When the timer goes off, switch the valve to the release position for quick release.
Stir the onions, peppers, tomatoes, cream cheese, and seasoning together until well mixed.
Add the heavy cream, cheddar, and Monterey Jack cheeses and stir until completely melted and smooth. Check the seasonings and adjust them to taste if necessary.
Transfer to a bowl and serve hot with desired toppings and your favorite dippers.
Enjoy your delicious Instant Pot Queso!