Place chicken breasts on the bottom of a crockpot, and add chili powder, cumin, onion powder, garlic powder, cayenne pepper, chicken broth, green chiles, corn and beans. Cook on low for 6-8 hours.
About an hour before serving: In a small saucepan, melt butter over medium high heat. Whisk in flour, and allow to bubble and brown a bit. After a few minutes, gradually whisk in the milk and chicken base.
Allow the sauce to simmer for 4-5 minutes, whisking frequently until it is slightly thickened. Add salt and pepper.
Pour sauce into crockpot and mix to combine.
Add sour cream and mix.
Take out the chicken and shred them with two forks, and return to the crockpot.
Top with cheese.
Serve with tortilla chips.
Sorry I don't have a picture. Picture coming soon!