Put all the burger ingredients in a bowl and mix well; it's easiest using your hands to get right in there; once it's suitably mixed, cover and leave at room temperature for 10 minutes.
Add the cream cheese and grated cheese into a separate bowl and mix well, trying not to eat it all before using it in the burgers.
Split the burger mix into 8 even parts and shape into thin(ish) patties; take a generous teaspoon of the cheese mix and place it in the centre of 4 of the patties. It's best to do all this at once because you're about to get your hand covered with raw meat.
Take a cheesy patty and a not so cheesy one and 'smush' them together (it's a technical term), making sure to squeeze the edges together so the burger becomes one solid 'ball' of meat with the cheese mix inside; I can't stress enough how vital it is that you make sure that there are no holes in the burger- we don't want that cheese mix escaping now do we?
Once you have four good looking raw burgers, wrap them individually in foil and chill the raw burgers in the fridge for 20 minutes to firm up.
Tidy up and preheat that oven to 180 degrees Celsius if you're using a griddle for cooking your burgers, I'm not sure how long it takes to warm up or cook, but I'm sure you can figure it out.
Pop the burgers on a grill pan and pop them on the middle shelf for 18 to 20 minutes until the burger is firm and juicy.
Add any extra cheese mix on the toasted rolls and serve your burgers on top.