In a large bowl combine meat, thyme Worcestershire and seasonings; cover with plastic wrap and let mingle in the refrigerator at least one hour.
Before grinding the meat, place the bowl in the freezer, and chill until meat is very cold, but not quite frozen; about 10 minutes (it’s more like 20 to 30 in my freezer).
Make sure all equipment touching the meat is cold.
Toss partially frozen beef in bowl to combine, and push meat through meat grinder using the coarse attachment.
After all meat is ground, grind again; this helps mix the different cuts thoroughly.
Make The Burgers
Quickly and loosely shape ground beef into 6 piles (approximately 3-4 ounces each), and press flat with the back of a spatula.
Don’t overwork or overshape the meat; you want loose, ragged strands, not a hard-pressed patty.
Heat a cast iron skillet over high heat until nearly smoking and add the butter.
Season hamburger patties heavily with salt and pepper, and place in the skillet, working in shifts if needed.
When burgers release from pan, flip and add American cheese to three patties, and Cheddar cheese to three patties.
Cover and cook until cheese melts, about two minutes.
Remove from heat and set aside to rest, while you assemble the buns.
Assemble
Toast your buns while burgers are cooking and smear with the condiments of your choice, in my case, just a bit of mayo.
Add a Cheddar-topped hamburger patty, then an American patty.
Top with onion.
Eat immediately. Growl a little, if you’d like. ( <– Finally! Someone who thinks like me!)
Notes
Adapted From Away (Seriously, go read this post – it’s amazing and you’ll learn a thing or two)