Place a large skillet over medium-high heat and add oil. Add diced chicken tenders and cook 3–4 minutes until exterior of chicken is no longer pink.
Add the diced onion and cook an additional 3–4 minutes until onion is softened and translucent.
Add entire can of diced tomatoes, including juice, drained black beans, corn kernels, garlic powder, oregano and cumin and bring to a bubble. Reduce heat to medium and cook at a rapid simmer for 2–3 minutes, stirring often.
Add entire can of enchilada sauce and chopped corn tortillas. Stir to combine and return to a boil. Reduce heat to medium-low and simmer, uncovered, stirring frequently, for 5–6 minutes or until hot and bubbly and tortillas break down and thicken sauce.
Remove from heat and give casserole one last stir and season to taste with salt and pepper. Sprinkle on shredded cheese and allow casserole to sit 5 minutes while cheese melts and sauce thickens up a bit more. Right before serving, sprinkle with chopped cilantro and sliced green onions.
Notes
Want to really indulge? Add a sunny-side-up egg on top of your finished casserole!