For the chili: Preheat the oven to 400°F. Mist a 9-inch baking pan with nonstick vegetable oil cooking spray. Heat a large skillet over medium-high heat, add the oil, and cook the turkey until it is no longer pink. Remove the meat from the skillet and drain if necessary. Heat the same skillet over medium-high heat, add 2 tablespoons of water, onions, peppers, and garlic, and cook until the vegetables are translucent. Add the chilies, beans, cumin, oregano, chili powder, and chicken stock. Cook for 1 to 2 minutes. Return the meat to the skillet and bring to a boil. Reduce heat and simmer for 3 to 5 minutes. Transfer the chili to the prepared baking pan.
For the cornbread topping: Combine the cornmeal, flour, salt, and baking powder in a large mixing bowl. In another bowl, whisk together the Ensure, water, oil, and egg. Mix together with the dry ingredients just to incorporate. Pour the batter over the turkey chili and sprinkle with the chopped scallions if desired. Bake for 20 to 25 minutes or until a toothpick inserted into the center of the bread comes out clean and the top is golden. Allow the casserole to stand for 7 to 10 minutes before serving.