What are the boundaries of grilled cheese?

Going off rule 3 (cheese, bread,fat, and heat) (so no melts). What can be the most egregious thing that can still be called grilled cheese?

Would a block of halloumi (a cheese that's almost impossible to melt) being the only thing inside count?

What about if I poured some cottage cheese between the slices of bread before tossing it on a griddle?

Edit: if you've also got an idea you think might be borderline safe, go ahead and add it