Preheat your Traeger Flatrock griddle to medium high.
Chop the chicken breasts into 3/4 inch cubes.
In a bowl, season the chicken with Truff hot sauce and Smoke Junkie seasoning.
Drizzle a bit of oil on the hot griddle.
Begin cooking the onion and red bell pepper on the griddle until translucent.
Add the chicken and continue cooking on the hot griddle until just cooked through.
Add the canned corn to the chicken on the grill and heat through.
Transfer the chicken to a bowl and turn off the griddle.
Stir in the crushed corn chips in the chicken mixture.
Preheat the Traeger Timberline XL to 375*.
In a bowl, combine the drained rotel with the cream of mushroom soup.
Briefly warm the cream cheese in the microwave (about 20 seconds).
Add the cream cheese to the soup mixture.
Assemble the casserole in a 9x9 pyrex dish.
Arrange a layer of toastada shells on the bottom of the dish.
Top with 1/2 of the chicken and 1/2 of the soup mixture.
Sprinkle generously with shredded cheese.
Repeat the layers, finishing with shredded cheese.
Top with sliced jalapenos.
Bake the casserole in the hot Traeger Timberline grill until bubbly throughout-- about 30 minutes.
Allow to cool briefly before slicing and serving.
Serve your Traeger grilled King Ranch Chicken Casserole with fresh cilantro and sliced avocado.