Melt the butter in a large pot over medium heat. Add the garlic and the onion and saute until softened, 5 minutes. Add the flour and stir well, cooking for 1 minute more. Add the broth and the half-and-half. Stir in the cream of chicken soup, salsa, chicken, beans, corn, cumin and fajita seasoning. Continue to simmer over low heat for 15 minutes.
Crumble the tortilla chips into individual bowls and top with a ladle of soup. Sprinkle each serving with cheese and add a dollop of sour cream.
Recipe adapted from Georgia Cooking in an Oklahoma Kitchen by Trisha Yearwood (c) Clarkson Potter 2008