Preheat the oven to 400°F.
In a large skillet over medium heat, cook the ground beef, onion, and garlic until the beef is browned and the onion is translucent, about 5-7 minutes. Drain excess fat.
Stir in salt, pepper, and Worcestershire sauce.
In a 9x13 inch baking dish, layer the cooked beef mixture evenly on the bottom.
Sprinkle shredded cheddar cheese over the beef.
Arrange the frozen tater tots in a single layer on top of the cheese.
Bake in the preheated oven for 25-30 minutes or until the tater tots are golden brown and crispy.
While the casserole is baking, prepare the Big Mac sauce by mixing mayonnaise, ketchup, yellow mustard, and chopped pickles in a small bowl.
Once the casserole is done, remove it from the oven and let it cool for 5 minutes.
Top with shredded lettuce, diced tomatoes, and drizzle with the Big Mac sauce. Serve warm.