Preheat oven to 500 degrees.
Heat a medium skillet on high heat. pour 1 tablespoon oil onto pan, pour chicken and onions. saute for 5 minutes. Add 1/4 cup BBQ sauce and saute for another 3-5 minutes until the chicken and onions begin to caramelize. Remove from heat and set aside.
In a small bowl, mix 1/4 cup ranch dressing and remaining 1/4 cup BBQ sauce. Set aside.
If making the pizza in a pan grease pan with oil and sprinkle with cornmeal or flour. Spread pizza dough into a large circle about 12 inch in diameter. Spread the BBQ/Ranch mixture on the pizza. Add the chicken and onion mixture. Sprinkle the toppings with 1 cup of mozzarella cheese.
Bake in low rack for 12-15 minutes. Remove from oven and slice.