Preheat your oven to 375°F and lightly grease a small baking dish.
Heat the olive oil in a skillet over medium heat and sauté the diced onion and bell pepper until softened and slightly caramelized.
In a small bowl, whisk together the tomato puree, ancho chili powder, garlic powder, cumin, sea salt, and black pepper to create the sauce.
Combine the shredded chicken breast with two tablespoons of the prepared sauce and the sautéed vegetables in a mixing bowl.
Warm the corn tortillas slightly to make them pliable, then dip each one into the sauce to coat both sides.
Place a portion of the chicken filling in the center of each tortilla, roll tightly, and place seam-side down in the baking dish.
Pour the remaining ancho chili sauce over the top of the rolled tortillas and sprinkle evenly with the shredded cheddar cheese.
Bake for 15 minutes until the sauce is bubbling and the cheese has completely melted.
Garnish with freshly chopped cilantro before serving hot.