Preheat oven to 350°F. Place one mini-muffin pan upside down on a baking sheet. Cut once slice of bacon into thirds. Cut one one-third piece lengthwise, into two narrow strips. Wrap the two narrow strips around the vertical sides of one of the upside-down muffin cups, overlapping the pieces so that they completely encircle the muffin cup. Drape one of remaining one-third slice bacon pieces across the muffin cup so that it overhangs the sides and covers the seams of the overlapping narrow strips. Repeat until all muffin cups are covered. Carefully place a second mini-muffin pan upside down, over the bacon, so that the bacon maintains its cupped shape while cooking. Place in 350°F oven until bacon is just crisp, about 35 minutes. If bacon appears under-done after 30 minutes, remove top muffin pan and cook bacon cups uncovered for an additional 5-10 minutes. Allow to cool 5 minutes and remove bacon cups to paper towel-lined plate to drain. Repeat with any leftover bacon, until you have made 16 cups. (Bacon cups can be made 4 hours in advance. Leave uncovered at room temp until ready to use.) Make ranch chicken filling In a medium bowl, whisk together mayonnaise, ranch dressing mix, and chopped dill. Stir in shredded chicken and chopped green onion until well combined. (Chicken mixture can be made 1 day in advance. Cover and refrigerate until ready to use) Assemble ranch chicken BLT cups Divide shredded lettuce evenly among bacon cups. Top with 2 teaspoons of ranch chicken mixture. Garnish each cup with a quarter slice of tomato and a sprig of dill. Serve immediately.