Chicken: Coat the tomatillos, tomatoes, onions, garlic, and jalapenos in 2 tablespoons of olive oil and spread them out on a sheet tray lined with parchment paper and roast in the oven for 35 to 40 minutes or until there is a light char on the vegetables.
Remove the ingredients and transfer them to a blender along with the cumin, oregano, salt and pepper, and puree until smooth. Set aside.
Next, season the chicken breasts on both sides with salt and pepper. Heat the remaining 1 tablespoon of olive oil in a large dutch oven pot until it begins to lightly smoke and add in the chicken breasts and brown on both sides.
Pour the blended tomatillo mixture over top of the chicken along with the chicken stock, salt and pepper and cook over low heat for 2 to 3 hours. Shred the chicken once it becomes easy to pull apart and keep warm.
To Make: Place the tortilla chips on a large sheet tray or divide it between 2 cast iron skillets and mix in the slow cooked shredded chicken until the tortilla chips are coated.