Preheat your oven to 375°F (190°C).
Heat the olive oil in a small skillet over medium heat and sauté the diced white onion until translucent and soft.
In a medium bowl, combine the shredded cooked chicken breast with the sautéed onion, chili powder, cumin, garlic powder, sea salt, and black pepper.
Stir in 2 tablespoons of the tomato puree into the chicken mixture to moisten the filling.
Warm the corn tortillas slightly in a dry pan or microwave to make them pliable for rolling.
Divide the chicken filling evenly between the two tortillas, roll them tightly, and place them seam-side down in a small baking dish.
Pour the remaining tomato puree over the top of the tortillas, spreading it evenly to cover the edges.
Sprinkle the shredded cheddar cheese over the sauce layer.
Bake for 15-20 minutes until the sauce is bubbling and the cheese has melted into a golden crust.
Garnish with fresh chopped cilantro before serving warm.