Preheat oven to 350 degrees.
Place frozen meatballs in large saucepan with BBQ sauce, over medium-low heat. Heat with lid covered for about 20-25 minutes, stirring occasionally. Add ¼ cup of water if sauce gets too thick. Set aside. (You can also use your slow cooker for even easier prep!)
Cook diced bacon in a skillet over medium heat until crispy. Drain bacon on paper towels to remove excess grease.
Cook sliced onion in same skillet used for bacon, until caramelized, about 8 minutes.
Place bottom half of biscuits in rectangular baking pan. Place 2 cooked meatballs on top of each biscuit.
Top with slices of cheddar cheese.
Place a small spoonful of bacon and onions on top of cheese and sprinkle green onions.
Melt butter in small bowl. Add a dash or two of Worcestershire sauce to butter and stir. Brush melted butter over the tops of the biscuits and sprinkle with shredded cheddar cheese.
Place sliders in preheated oven to heat through and melt the cheese, about 8-10 minutes.
Remove from oven. Spear with toothpick and Kosher Pickle and serve.