Chicken, apple, caramelized onion flatbread with balsamic glaze

In a mixing bowl, add all of the poolish ingredients and stir until well combined. Cover and leave at room temperature for 1 hour. Place in the refrigerator for 2-16 hours. This can be done the night before or the morning of for best results giving the poolish time to ferment.

Take the poolish from the refrigerator and add in 154ml water, stir till combined.
Add and mix in approximately half of the 324g all-purpose flour and all of the salt stirring to combine. Add in the remainder of the flour and work the dough in the bowl until a shaggy dough ball forms. Pour out the dough onto a clean work surface and cover it with the bowl. Let rest for 15 minutes.
Put some olive oil on your hands and work the dough into a smooth dough ball. Place the dough in an oiled bowl and cover, rest for 30 minutes.
Place the dough ball on your clean work surface and cut it with a dough knife into 4 equal parts. Form the equal parts into dough balls and place them on a floured cookie sheet with space around each ball. Gently apply olive oil to the tops of each ball and cover the cookie sheet with plastic. Rest for 2 hours.
One hour before baking the flatbreads, preheat your oven to 550°F with a pizza stone or pizza steel in it. If you don't have access to one of these, preheat the oven to 400°F and bake the flatbread on a cookie sheet.

Cut the large red onion in half splitting the onion into 2 equal parts, dividing it through the root. Peel back the outer layer and chop the onions into half circles about ⅛ inch thick.
Heat 1 tbsp olive oil over medium heat and add the onions. Stir every few minutes for even cooking. The goal is to soften and caramelize, not burn. Reduce the temperature if the onion blackens at all. Set aside to use as a topping.

Flatten the chicken with a meat mallet or your fist in a sealed plastic bag. Once it is even thickness, season one side with salt and pepper to taste.
Add 1 tbsp ghee to a stainless or carbon steel pan over medium-high heat until shimmering. Add the chicken and allow to cook for 5-7 minutes before you flip. Remove the chicken to rest once it has reached an internal temperature of 155°F on an instant-read probe thermometer. Use Stainless steel or carbon steel, or even maybe cast iron because the browned bits left in the pan called fond are going to help in making the pan sauce.

Add the shallot and garlic to the pan you used to cook the chicken stirring and cooking for a minute until fragrant.
Add the wine to the pan and scrape with a wooden spatula to release all of the browned bits.
Add the chicken broth and butter and simmer for several minutes softening and cooking the shallots and garlic, and reducing the broth.
Whisk together the milk and cassava flour and add them to the pan sauce while whisking. Last, add the capers. Remove from heat and set aside to use as the sauce for the flatbread. The consistency should be thin gravy, if its too thick, add more broth.

Place one of your dough balls on a well-floured surface and roll it out with a rolling pin into a rectangular shape. Sprinkle your pizza peel with brown rice flour or cornmeal. Lay the dough on the pizza peel and shake the peel making sure that the dough slides around and doesn't stick.
Add a few serving spoons of the sauce to the dough and top with sliced chicken, apple slices, caramelized onions, and just a few pinches of the grated mozzarella cheese.
Bake the flatbread in your oven for several minutes until the dough begins to brown. Remove from the oven and rest for a few minutes before cutting it and serving.
NOTE: If you are baking your flatbread on a cookie sheet, roll the dough out on a piece of parchment paper, then transfer that to the cookie sheet before adding your toppings. This will keep your cookie sheet clean.