Preheat the oven to 350 F. Grease a 9x13-inch casserole dish.
Season the chicken with salt and pepper.
Heat olive oil in a non-stick skillet on medium-high heat and sear chicken with onion for 2 minutes.
Add green chili and sweet corn. Cook for another minute. Remove from heat.
Assemble the enchiladas by laying the tortillas on a flat surface. Spread 2-3 tablespoons of salsa sauce on each tortilla.
Divide the chicken filling into 8 equal portions to fill up the tortillas, and sprinkle with 3–4 tablespoons of cheese.
Roll up and place in your greased baking dish.
Add the remaining sauce on top of the enchiladas and sprinkle with the rest of the shredded cheese.
Bake the chicken enchilada casserole uncovered in the middle of the oven for 20 minutes until the cheese melts and the enchiladas are cooked through.
Remove and garnish with fresh cilantro or green onions. Serve immediately.