To make Chili's baked potato soup, preheat the oven to 400 F ,and bake 2 cups of chopped potatoes for approximately 1 hour. Remove the potatoes, and allow to cool. In the meantime, start preparing the soup by melting 3 tablespoons of butter in a large saucepan.
Add 1 cup of diced white onion to the pan, and saute until golden brown. Add 2 tablespoons of white flour, and combine to make a roux. Next, add 4 cups of chicken stock, 2 cups of water, 1/4 cup of cornstarch and
1 1/2 cups of mashed potatoes. Season with 1 teaspoon of salt, 3/4 teaspoon of pepper, 1/2 teaspoon of basil and 1/8-teaspoon of thyme. Bring to a boil; reduce heat and continue to simmer for 5 minutes.
Cut the cooled potatoes in half lengthwise. Scoop out the insides and discard the skins. Chop the baked potato into 1/2 inch chunks, then add the chopped baked potato and 1 cup of half-and-half to the saucepan. Return the soup to a boil, reduce heat and simmer for about 15 minutes.
To serve, spoon the soup into bowls, and garnish with approximately 1 tablespoon of shredded cheddar cheese, 1/2 tablespoon of crumbled bacon and 1 teaspoon of chopped green onion.