Preheat your oven to 375°F (190°C).
Heat the olive oil in a skillet over medium heat. Add the diced bell pepper and onion, sautéing until softened and slightly caramelized.
While the vegetables cook, shred the cooked chicken breast into bite-sized pieces.
In a mixing bowl, combine the red enchilada sauce, Greek yogurt, diced green chilis, cumin, chili powder, sea salt, and black pepper. Stir until smooth and creamy.
Fold the shredded chicken and sautéed vegetables into the creamy sauce mixture.
Cut the corn tortillas into quarters. In a small oven-safe baking dish, layer half of the tortilla pieces on the bottom.
Spread half of the chicken and sauce mixture over the tortillas. Repeat with the remaining tortillas and the rest of the chicken mixture.
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 rest for 5 minutes before serving.