Preheat your oven to 375°F.
Season the chicken breast with half of the sea salt and black pepper, then bake or poach until fully cooked and shred it using two forks.
In a small saucepan, heat the olive oil over medium heat and whisk in the ancho chili powder, ground cumin, garlic powder, and onion powder for 30 seconds to bloom the spices.
Stir in the tomato puree and chicken broth, simmering for 5 minutes until the sauce is slightly thickened and fragrant.
In a medium bowl, toss the shredded chicken with 2 tablespoons of the prepared ancho sauce.
Warm the corn tortillas briefly in a dry skillet or microwave until they are soft and pliable.
Place a portion of the chicken mixture into each tortilla, roll them up tightly, and arrange them seam-side down in a small baking dish.
Pour the remaining ancho chili sauce over the tortillas and sprinkle evenly with the shredded cheddar cheese.
Bake for 12 to 15 minutes until the cheese is melted and the sauce is bubbling.
Top the finished enchiladas with sliced avocado, diced red onion, and fresh cilantro before serving.