In a large mixing bowl, using a fork, mix together the olive oil, salt, cumin, chile powder, tomato paste, oregano and cayenne until thoroughly mixed. Add the chicken thigh and toss until the thighs are well coated in the spice mixture. Let marinate for at least an hour or up to 12.
Preheat grill to high. Once hot, add the chicken to the grill and cook for 4-6 minutes per side or until cooked. Remove the chicken to a plate and let rest for 10 minutes. Turn the grill heat down to medium. Once the chicken has rested, chop the chicken into 1/2-inch pieces. Set aside.
Tear off four big square piece of aluminum foil. Place about two cups (two big handfuls) of tortillas chips in the center of a sheet of foil. Top the chips with ¼ of the Monterey Jack cheese, ¼ of the chopped chicken and then ¼ of the cheddar cheese. To seal the packets, bring two sides of the foil together over top of the nachos and roll them together to create a seal. Roll up the open sides of foil packets to seal together all the edges. Repeat with the rest of the ingredients to make four foil packets. You could easily stretch the ingredients to make six foil packets, if you're serving this as a snack or a side dish.
Place the foil packets onto the grill and let cook for 8-10 minutes or until cheese melts (it’s OK to peek inside the pouch if you’re unsure). When ready, remove from the grill, carefully open the packets and top with your favorite toppings.
Grant Melton is an Emmy Award-Winning Producer of the Rachael Ray Show, food writer and recipe developer. He's a contributor to Food52, Food Network Kitchen and Rachael Ray Every Day Magazine. His favorite food is chocolate chip cookies (with salt.)