BBQ Chicken Potpie With Cornbread Crust

Name: BBQ Chicken Potpie With Cornbread Crust
Ingredients: 1 tablespoon olive oil; 1 tablespoon unsalted butter; 2 cups chopped onion; Two 4.5-ounce cans of chopped green chilies; 1 teaspoon minced garlic; 2 teaspoons cumin seeds; 1 teaspoon ground coriander; 1/4 cup vinegar (preferably cider vinegar); 5 previously cooked chicken legs, shredded; 2 tablespoons brown sugar; 1-ounce unsweetened chocolate, finely chopped; One 12-ounce bottle chili sauce; 1 cup chicken broth; 2 boxes cornbread mix (I use Jiffy); 2 large eggs; 2/3 cup milk (water or chicken broth also work well); Salt and pepper to taste