Preheat your oven to 375°F (190°C).
In a small saucepan over medium heat, add the olive oil and sauté the diced yellow onion and minced garlic until softened and translucent.
Stir in the ancho chili powder, cumin, sea salt, and black pepper, cooking for 1 minute until fragrant.
Add the tomato puree and chicken bone broth to the saucepan, whisking to combine; simmer for 5-7 minutes until the sauce thickens slightly.
Place the cooked, shredded chicken breast in a small bowl and toss with 2 tablespoons of the prepared ancho sauce to coat.
Lightly warm the corn tortillas in a dry skillet or microwave to make them pliable.
Fill each tortilla with the shredded chicken mixture, roll tightly, and place 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 12-15 minutes until the cheese is melted and the sauce is bubbling.
Remove from the oven and garnish with freshly chopped cilantro before serving.