These basic burgers are cooked to your liking in a cast iron skillet--no grill required!
Combine all ingredients but the butter and optional cheese in a medium mixing bowl. I know it's not glamorous, but "clean hands are a cook's best tool" definitely applies here.
Divide into four patties, about 3/4 inch thick. Place on a cutting board, plate, or baking sheet and slide into the freezer for 15 minutes. This helps the burgers firm up and hold together better while cooking.
While the burger patties are in the freezer, preheat a cast iron skillet over medium heat on the stove. Melt the butter in the pan right before you're ready to cook.
Add burgers to the pan straight from the freezer and cook for 3 to 5 minutes. Depending on the size of your cast iron skillet, you may need to do this in batches. Flip the burgers when they're as brown as you want them and add cheese on top if you'd like. Cover the skillet with a lid, and cook for another 3 to 5 minutes. I like my burgers well done, so I cook for close to 5 minutes on each side, but if you like them medium or rare, ease off on the cooking time.