Preheat the oven to 375°F (190°C) and grease a 9x13-inch baking dish.

In a large skillet, heat olive oil over medium heat, add chicken breasts, and cook for 12-15 minutes until cooked through. Remove chicken and shred.

In the same skillet, sauté diced onion, garlic, and bell pepper for 5-7 minutes until soft.

In a mixing bowl, combine shredded chicken, cream cheese, sour cream, and half of the enchilada sauce.

Layer 4 corn tortillas at the bottom of the greased baking dish, followed by half of the chicken mixture and half of the sautéed vegetables.

Add another 10 tortillas on top, pour the remaining chicken mixture and sautéed vegetables, drizzle with remaining enchilada sauce, and sprinkle with cheddar cheese.

Bake in the preheated oven for 35-40 minutes until bubbly and golden. Let rest for 10 minutes before slicing.