Preheat your oven to 375°F (190°C) and lightly grease a small baking dish.
Heat the olive oil in a skillet over medium heat and sauté the diced onion and minced garlic until softened and fragrant.
Whisk in the tomato puree, chicken broth, ancho chili powder, cumin, sea salt, and black pepper, then simmer for 5-7 minutes until the sauce slightly thickens.
In a mixing bowl, combine the cooked shredded chicken with 3 tablespoons of the prepared ancho sauce to keep the filling moist.
Briefly warm the corn tortillas in a dry pan or microwave to make them pliable.
Place a portion of the chicken mixture into each tortilla, roll them up tightly, and place them seam-side down in the baking dish.
Pour the remaining sauce over the top of the tortillas and sprinkle evenly with the shredded sharp cheddar cheese.
Bake for 15 minutes until the cheese is melted and the sauce is bubbling.
Garnish with freshly chopped cilantro before serving.