Place chicken breasts, 1/2 of the enchilada sauce (5 oz), diced green chiles, chopped onion, minced garlic, chili powder, cumin, salt, and pepper into a 6-quart or larger slow cooker.
Stir gently to combine ingredients around the chicken. Cover and cook on low for 3-4 hours or on high for 2-3 hours, or until chicken is easily shredded.
Remove chicken from the slow cooker and shred it using two forks. Return the shredded chicken to the slow cooker and stir well to combine with the sauce mixture.
Spray the bottom of the slow cooker with non-stick spray.
Spread about 1/4 cup of the remaining enchilada sauce on the bottom of the slow cooker.
Warm tortillas slightly (microwave for 15-20 seconds per stack) to make them more pliable.
To assemble enchiladas: Take one tortilla, add a spoonful of the chicken mixture and a sprinkle of shredded cheese. Roll it up tightly and place seam-side down in the slow cooker. Repeat with remaining tortillas, arranging them snugly in the slow cooker.
Pour the rest of the enchilada sauce over the rolled enchiladas and sprinkle generously with the remaining shredded cheese.
Cover and cook on low for an additional 30 minutes to 1 hour, or until cheese is melted and bubbly and enchiladas are heated through.
Serve hot, garnished with desired toppings.
Notes
Ensure your slow cooker is at least 6 quarts for this recipe.
Adjust the spice level of the enchilada sauce to your preference.
Warming the tortillas makes them easier to roll and less likely to crack.
You can prepare the chicken mixture ahead of time and refrigerate it for quicker assembly later.
Feel free to add other vegetables like bell peppers or corn to the filling.