So, since I’m the one that sent boxo to Ted’s as a former resident of the Meriden/Wallingford area of Connecticut where you find these, let me clear up a few things. Ted’s like K Lamay does use white cheddar for their burgers. It’s a proprietary recipe.

Second, I’d consider the southern “version” of this to be Krystal not White Castle as I don’t remember seeing any White Castles around living down there but Krystals everywhere.

Now, for duplicating the steamed cheeseburger... I probably wouldn’t have used an Instant Pot. The temperature was likely too high and that’s why it dried out. The steam cabinets are atmospheric pressure steam or just a little hotter. The cheese is usually in a separate container and it has to be scraped out to be put on the burger. I’ve never had one that was mealy but they do look a little grey.

The other thing that could have made it dry was what type of beef was used. I don’t think that they use a lean ground beef which would help it stay moist. shows how I would do it.