Preheat the oven to 375°F.
Add the butter to a heavy-bottomed pot, and once melted, add the sliced onions and sea salt. Stir to combine, turn the heat to medium-low, and place a lid on top. Let the onions cook until caramelized (45 minutes to 1 hour), stirring occasionally.
While the onions are caramelizing, place the chicken breast in a baking dish, toss it with a ¼ cup of BBQ sauce until fully coated, and then sprinkle the sea salt, smoked paprika, and ancho chili powder over top. Place an in-oven thermometer probe into the thickest part of the chicken, and bake at 375°F until the internal temperature reaches 165°F (about 25 minutes). Once the chicken is out of the oven, adjust the oven temperature to whatever temperature is needed to bake the pizza. Our dough calls for 400°F.
Let the chicken rest for about 10 minutes, then chop it into 1-inch pieces. Put the chopped chicken back into the dish it baked to sit in the juices and pan drippings until you are ready to assemble the pizza.
Once the onions and chicken are finished, roll the pizza dough out onto a parchment-lined sheet pan. If the dough is sticky, sprinkle it with a little bit of flour (no more than about 1 teaspoon). Use your fingers to form a crust around the perimeter of the pizza.
Pour ½ of a cup of BBQ sauce onto the pizza dough and use a spoon to spread it out. Then, layer on the shredded mozzarella cheese, followed by the cubed BBQ chicken, and finally, the caramelized onions.
Place the pizza in the oven and bake according to the pizza dough package instructions.
Once the pizza is out of the oven, garnish it with homemade ranch dressing and cilantro. Slice and enjoy!