In a large skillet set over medium heat, cook the chopped bacon until it reaches a crispy texture. Remove the bacon pieces and place them on a paper towel-lined plate to drain. Discard excess bacon grease, leaving approximately one tablespoon in the skillet.

To the same pan, add the ground beef and diced onion. Sauté the mixture for 6 to 8 minutes, until the beef is no longer pink and the onion has softened. Stir in the minced garlic, salt, and pepper, and continue to cook briefly until fragrant.

Incorporate the ketchup, mustard, Worcestershire sauce, and the reserved cooked bacon into the beef mixture. Stir thoroughly to combine all ingredients.

Reduce the heat to low and fold in the cheddar cheese soup and sour cream. Mix until the contents are smooth and creamy, then take the pan off the heat.

Preheat the oven to 375°F (190°C). Lightly grease a 9x13-inch baking dish. Spread the beef mixture evenly across the base of the dish. Scatter 1 cup of shredded cheddar cheese over the beef layer. Neatly arrange the frozen tater tots in a single layer over the cheese.

Place the dish in the preheated oven and bake, uncovered, for 35 to 40 minutes or until the tater tots are crisp and golden.

Remove from the oven and sprinkle the remaining 1 cup of shredded cheddar cheese evenly across the top. Return to the oven for an additional 5 minutes, or until the cheese has fully melted and is bubbling.

Allow the casserole to rest briefly before serving. If desired, garnish with sliced green onions for a fresh finishing touch.