Position the top oven rack in the center position and pre-heat oven to 425°F.

Place the potatoes in the pre-heated oven and bake until cooked through, approximately 50 minutes.

While the potatoes are baking, heat two tablespoons olive oil and the butter in a large skillet over medium heat. Once hot, add the onion and rosemary and season with salt and black pepper, to taste. Cook, stirring occasionally, until the onions are a deep, rich brown, approximately 45-50 minutes.

Deglaze the skillet by adding the balsamic vinegar and gently scraping up any brown bits off the bottom with a spatula. Remove from heat and set aside.

When cook time is complete, remove potatoes from oven and transfer to a baking rack to cool for 10 minutes or until cool enough to handle.

While the potatoes are cooling, combine the caramelized onions, shredded chicken breast, and BBQ sauce in a large bowl. Stir to combine and set aside.

Once cool, cut the potatoes in half lengthwise and carefully scoop out the soft interior with a spoon, leaving a one-quarter inch margin around the skins. (Save the cooked potato filling for another recipe).

Remove the baking sheet from the oven and flip over the skins with tongs. Divide the BBQ chicken and onion mixture evenly between the potato skins and top each with an equal amount of Mozzarella cheese.

Place the baking sheet back in the oven for another 10-15 minutes or until the cheese is golden brown and bubbly. Remove from oven and garnish with fresh parsley right before serving. Enjoy!