Heat 2 tablespoons olive oil in a medium skillet over medium heat. Add 1 medium yellow onion (diced) and cook, stirring occasionally, until softened and starting to turn golden, about 4 to 5 minutes. Add 3 cloves garlic and cook for another 30 seconds, just until fragrant.
Transfer the onion and garlic to a 6 quart or larger slow cooker. Add 1½ pounds boneless skinless chicken breasts, 4 cups low sodium chicken broth, 30 ounces great northern beans, 8 ounces diced green chiles, 1 ½ cups frozen corn , 2 teaspoons ground cumin 1 teaspoon dried oregano, 1 teaspoon chili powder, 1 teaspoon kosher salt, ½ teaspoon freshly cracked black pepper, and ¼ teaspoon cayenne pepper (if using). Stir gently to combine.
Cover and cook on low for 6 to 7 hours, until the chicken is cooked through and shreds easily with a fork.
Transfer the chicken to a cutting board or large plate and shred it into bite sized pieces using two forks. Return the shredded chicken to the slow cooker and stir to combine.
In a medium bowl, toss 8 ounces pepper jack cheese with 1 tablespoon cornstarch until evenly coated.
Turn the slow cooker to low heat if it isn't already there, or switch it off entirely if your model runs hot on low. Add 4 ounces cream cheese, stirring until it's mostly melted and smooth, about 2 to 3 minutes. Add the cornstarch coated pepper jack a handful at a time, stirring well after each addition and letting it fully melt before adding more, about 5 minutes total. Adding the cheese gradually over low heat instead of all at once keeps the fat and protein in the cheese from separating out into a greasy or grainy texture.
Let the chili rest for 5 minutes before serving so it can thicken slightly. Ladle into bowls and top with chopped cilantro and a squeeze of fresh lime juice, if desired.