Gently press the beef mixture into an ungreased 8-inch square glass or ceramic pan.
Bake until cooked through, 12-15 minutes. A meat thermometer should read 160°F. If there's a lot of cooking liquid in the pan, you can drain some. I like to keep it and allow some of it to get absorbed back into the burgers as they rest.
Top the cooked meat with the cheese slices.
4 slices sharp cheddar
Return the pan to the oven and bake just until the cheese is melted, for 1-2 minutes.
Remove the pan from the oven and allow the burgers to rest for 5 minutes. Cut into four squares and serve.
Video
Notes
Seasonings, especially salt, are guidelines. Adjust to taste
I typically use lean ground beef (85/15). Extra-lean (90/10) ground beef can be tricky in this recipe. It's drier and can also be more crumbly.
Although I recommend using an 8-inch square pan, I sometimes double the recipe and use two pans. One of the pans I own is a square 9-inch pan, so I use both and bake them at the same time. This works just fine, although the burgers baked in the 9-inch pan are slightly flatter.
The best way to make sure the burgers are done is to use an instant-read thermometer. It's OK to pull them out of the oven when they reach an internal temperature of 155°F, since you will return them to the oven to melt the cheese, at which point they should reach 160°F.
You can keep the leftovers in a sealed container in the fridge for 3-4 days. Reheat them gently in the microwave at 50% power, or enjoy them cold.