Preheat your oven to 375°F and lightly grease a small baking dish.
Heat olive oil in a skillet over medium heat and sauté the diced white onion until soft and translucent.
In a small bowl, whisk together the tomato puree, chicken broth, ancho chili powder, garlic powder, onion powder, cumin, sea salt, and black pepper to create the sauce.
Toss the shredded chicken breast with two tablespoons of the prepared sauce and the sautéed onions.
Warm the corn tortillas briefly in a dry skillet or microwave to make them pliable.
Dip each tortilla into the remaining sauce, fill with the chicken mixture, roll tightly, and place seam-side down in the baking dish.
Pour the remaining sauce over the top of the enchiladas and sprinkle with shredded Monterey Jack cheese.
Bake for 15 minutes until the sauce is bubbling and the cheese has melted beautifully.
Garnish with freshly chopped cilantro before serving.