Start by placing the boneless skinless chicken breasts in your slow cooker or Instant Pot. Pour in the chicken broth and sprinkle with poultry seasoning. Cook on low for 6-8 hours or high for 3-4 hours until the chicken is fully cooked and tender.
Once cooked, remove the chicken from the cooker and shred it using two forks. Return the shredded chicken to the pot to keep it moist.
In a large saucepan, pour the two cans of green chile enchilada sauce. Simmer over medium heat until the sauce reduces to about 2 cups, concentrating its flavor.
In a mixing bowl, combine the shredded chicken, cream cheese, sour cream, 1 cup of the Four Cheese Mexican Blend cheese, and half of the reduced enchilada sauce. Mix until well combined and creamy.
Preheat your oven to 350°F (175°C). Take a tortilla and spoon a generous amount of the chicken mixture onto it. Roll it up tightly and place it seam-side down in a baking dish. Repeat with the remaining tortillas and filling.
Once all enchiladas are in the dish, pour the remaining enchilada sauce over them. Sprinkle the remaining cheese blend and mozzarella cheese on top.
Bake the enchiladas in the preheated oven for about 25-30 minutes, or until the cheese is melted and bubbly.