Preheat oven to 375°F. Brush the bottom and sides of a 12 inch cast iron skillet with olive oil. Set aside. (Alternately, spray a 12 x 8 inch baking dish with cooking spray.)
Cook bacon on the stove top in a large skillet until crispy. Remove to paper towels to drain, then crumble. Reserve 3 Tbsp drippings in skillet.
Cook ground beef and onion in bacon drippings over medium-high heat until no pink remains. Add garlic cooking for 1 minute longer. Drain excess fat from pan.
To the beef add Worcestershire sauce, steak seasoning, salt and pepper. Mix well, remove from heat.
Add soup plus ½ soup can of milk, sour cream, ketchup, dill pickles, mustard and ½ cooked bacon. Mix until fully combined.
To assemble: Arrange ½ tater tots on bottom of skillet, top with ½ shredded cheese. Spread ground beef filling over cheese. Sprinkle with remaining bacon and cheese. Arrange reserved tater tots on top.
Bake for 30-40 minutes until bubbly around the edges and tater tots are golden.
Serve immediately garnished with green onion.