Place the diced chuck in a large bowl.
Set a 10-inch saute pan over medium heat and add the bacon. Cook, stirring occasionally, until the bacon is crisp and most of the fat has been rendered, 7 to 8 minutes. Add the onions to the pan and cook until they are softened, 4 to 5 minutes. Add the garlic and cook until fragrant, 1 minute longer. Add the thyme and toss to combine. Remove the pan from the heat and pour the mixture over the diced chuck. Drizzle with the Worcestershire, and season with the salt and pepper. Toss gently but thoroughly to combine. Cover and set aside to marinate, refrigerated, for 1 hour.
Assemble a home grinder according to the manufacturer's instructions, using a medium die for grinding. Grind the meat mixture and then gently form it into 4 patties, being careful not to overwork it. Cover and refrigerate until chilled, about 1 hour.
Preheat a grill to medium, and lightly oil the grate.
Remove the patties from the refrigerator and place them on the grill. Cook for 7 to 8 minutes. Then turn them over and place 2 slices of the cheddar on each burger. Cook for another 7 to 8 minutes for medium-rare to medium, or until the burgers are cooked to the desired degree of doneness. Place a burger on the bottom of each of the 4 toasted buns. Dress with the lettuce and tomatoes, and add mayo, ketchup, mustard, and pickles as desired. Serve immediately.