Preheat your oven to 375°F (190°C) and lightly grease a small oven-safe baking dish.
Dice the chicken breast into small pieces. In a skillet over medium heat, add the olive oil and sauté the chicken until cooked through and lightly browned.
Add the diced bell pepper and yellow onion to the skillet, cooking for 3-4 minutes until the vegetables are tender-crisp.
In a small mixing bowl, whisk together the red enchilada sauce, Greek yogurt, chili powder, cumin, sea salt, and black pepper until smooth.
Stir the cooked chicken and vegetable mixture into the sauce bowl until every piece is thoroughly coated.
Cut the corn tortilla into small bite-sized strips or quarters.
Layer half of the tortilla pieces at the bottom of the baking dish, followed by the chicken mixture, and then the remaining tortilla pieces.
Sprinkle the shredded cheddar cheese evenly over the top.
Bake for 15-20 minutes until the sauce is bubbling and the cheese has melted into a golden crust.
Remove from the oven and let it rest for 5 minutes before garnishing with fresh chopped cilantro.