Start by caramelizing the onions. Heat 1 tablespoon of olive oil over medium heat and add in diced onions, letting the onion soften and turn a golden brown (about 5 minutes).
Add the brown sugar and balsamic vinegar to the pan and stir to coat the onions, letting them caramelize even further (about 2 minutes). Remove pan from heat.
Combine ground chicken, egg, breadcrumbs, parsley, garlic, salt and pepper in a large bowl. Add the caramelized onions and mix completely.
Form the chicken mixture into 12 equal size mini-patties. Grill the patties over medium high heat for 3 to 5 minutes per side, or bake on a lightly greased baking sheet in a 400 degree oven for 10 minutes, flipping over half way.
Top each chicken patty with 1/4 slice of cheese, followed by two small pieces of cooked bacon and another 1/4 slice of cheese.
Slice KING’S HAWAIIAN rolls in half horizontally, spread HEINZ mayo on bottom side. Place sliced California avocado then chicken patty. Separate sliders and serve.