Into a slow cooker add chicken (if using), corn, cream cheese, sour cream, jalapenos, garlic powder and tajin. Cook on low for 5-6 hours. I always avoid high heat when using cream cheese and sour cream as the crock pot can get too hot and "break" the dairy, creating tons of unsightly lumps.
Mix the ingredients together until smooth (shredding the chicken if using), add in most of the shredded cheese, reserving 1/2 cup. Add in the lime juice and zest, chipotle powder and mix well until incorporated. Taste and adjust flavor as needed.
Top with remaining shredded cheese, cover and keep on low for another 20-30 minutes or until cheese melts through.
To finish off the dip, add all of the toppings - cojita cheese, scallions, cilantro, hot sauce, etc. Serve with tortilla chips.