Dear 100 Hour Board,
How does a slice of Costco cheese pizza have more calories than a slice of their other flavors of pizzas?
You're in luck, because Luciana answered this a few months ago! You can find her very comprehensive answer here.
I can add a second witness that Costco's cheese pizzas are incredibly cheesy. In general cheese tends to be more calorie-rich than meats, so loading on a lot of extra cheese makes a pretty big caloric difference.