Dang, Cliff... I’ve seen those sheet pan burgers before but have never made them myself. That has got to change!!!! How many lbs of beef would you say it takes to fill the pan in that pan?
You can fill them up to make them as thick or thin as you like. As a guide, a normal sized sheet will yield 12 patties, so:
> 3 lbs of meat will give you 1/4 lb patties (pre-cooked weight). < a good size for cookouts with other meats being served
> 4 lbs will give you 1/3 lb patties. < a good size if this is your main protein (especially with toppings).
What temp do you cook at, and about how long do you plan on the cook taking?
Anywhere from 225° - 300° seems to work well. The lower & slower you go the more smoke they can absorb. It depends on what if anything else is being cooked with them, and/or what toppings you're using. They need to cook as well.
Overall, though I find low & slow 225° - 250° is best, especially if you have bacon on top.
Is the beef not just swimming in its own fat when done?
Oh you better believe they're swimming in their own fat & juices.
HOWEVER the burgers, themselves, are NOT any more/less greasy than cooking them any other way. They do stay pretty juicy this way!
If there's an excess amount of fat & juices, then a turkey baster works well to get some of them out before trying to take them out of the grill.
One more note: The trade off with this method is you give up a crust for flavor, but the cheese, as well as the burger has a chance to pick up some smoke and the flavor is just absolutely phenomenal!
After doing this once, I guarantee it will, at the very least, find a place in your normal repertoire!