In a saucepan, heat the olive oil over medium heat. Add the garlic and onion; cook for 2-3 minutes, until slightly softened. Add the chicken, cumin, oregano, white pepper, and red pepper flakes. Season with salt and 1-2 teaspoons freshly ground black pepper. Cook, stirring, until the chicken is slightly browned, 3 to 4 minutes.
Add the collard greens and cook, stirring occassionally, until they are slightly wilted, about 5 minutes.
Add the chiles and chicken broth and bring to a boil, stirring occassionally. Reduce the heat to medium-low; cook, stirring occassionally, for approximately 20 minutes, until slightly thickened. Stir in the beans and cook for another 10 minutes. Stir in the cilantro.
Transfer the chili to bowls and garnish with sour cream, chopped tomatoes, and or lime wedges for garnish. My family and I also love to top with fresh slices of avocado. Enjoy!