Step 1: Heat olive oil in a large Dutch oven or heavy-bottomed pot over medium heat. Add chopped onion and cook until softened, about 5-7 minutes.nStep 2: Add minced garlic and jalapeño (if using) and cook for another 1-2 minutes until fragrant.nStep 3: Add chicken breasts or thighs to the pot. Cook until lightly browned on all sides, about 5-7 minutes. The chicken doesn't need to be cooked through at this stage.nStep 4: Stir in cumin, chili powder, dried oregano, and cayenne pepper (if using). Cook for 1 minute, stirring constantly, until aromatic.nStep 5: Pour in chicken broth, then add rinsed and drained beans and diced green chilies. Bring the mixture to a simmer, then reduce heat to low, cover, and cook for 15-20 minutes, or until chicken is cooked through and easily shredded.nStep 6: Carefully remove the chicken from the pot and shred it using two forks. Return the shredded chicken to the chili.nStep 7: Stir in the softened cream cheese cubes until completely melted and incorporated, making the chili creamy. Gradually stir in the milk or half-and-half until the chili reaches your desired consistency.nStep 8: Season the chili with salt and freshly ground black pepper to taste. Continue to simmer for another 5 minutes to allow flavors to meld.nStep 9: Ladle the creamy white chicken chili into bowls. Garnish generously with fresh cilantro, shredded cheese, a dollop of sour cream or Greek yogurt, and diced avocado, if desired. Serve hot and enjoy!