Take your chicken breast and slice a pocket into them about 2-3 inches deep and about the whole length of the chicken for the stuffing. Mix together your cream cheese, green chiles and shredded cheddar. Stuff the chicken with 2-3 tbsp of the cream cheese mixture, then pin the opening with a toothpick. Lather the outside of the chicken in oil and season with salt and pepper. Repeat this with all the chicken, then place in the fridge for 30 minutes to set.
Preheat your grill for two zone medium heat indirect cooking (around 325F).
Add your chicken to the cool side of the grill to cook for about 1-1.5 hours until they reach 165F internal. Once the chicken is cooked, heat up your coals for high heat (around 400F). Add the cooked chicken plus the tomatillos over the hot coals to sear for about 1.5 minutes per side until crispy. Once done, pull the chicken and tomatillos off the grill to rest.
As the chicken rests, add the tomatillos and the rest of the tomatillo salsa to a food processor and blend until smooth.
Slice your chicken, top with the salsa and enjoy!