Preheat your oven to 375°F and lightly grease a small oven-safe baking dish.
Sauté the chicken breast in olive oil over medium heat until cooked through, then shred finely using two forks.
In a medium bowl, whisk together the Greek yogurt, tomato sauce, green chilis, chili powder, cumin, garlic powder, salt, and pepper.
Fold the shredded chicken into the yogurt mixture until every piece is thoroughly coated in the creamy sauce.
Cut the corn tortillas into one-inch strips.
Place half of the tortilla strips in the bottom of the baking dish, top with the chicken mixture, and layer the remaining strips on top.
Sprinkle the shredded cheddar cheese evenly over the top layer.
Bake for 15 minutes until the cheese is melted and the sauce is bubbly.