Preheat oven to 400 degrees. In a medium skillet over medium heat, melt the butte and the stock. Saute the corn for 1-2 minutes then add the chicken, spices, and season. Remove from heat and mix in scallions if using. Halve the avocado and remove pit. Squeeze lime over the halves and lightly season. Top each have with the chicken mixture and sprinkle with shredded cheese, place in the oven until cheese is melted. Remove from oven and garnish with tomatoes and cilantro.