Preheat oven to 375°F.
In a small saucepan, heat olive oil over medium heat, then whisk in chili powder, cumin, garlic powder, onion powder, salt, and pepper.
Stir in tomato puree and simmer for 5 minutes to allow flavors to meld into a smoky sauce.
Place the cooked shredded chicken in a bowl and toss with 2 tablespoons of the prepared red sauce and half of the diced white onions.
Briefly warm the corn tortillas in a dry skillet until pliable.
Fill each tortilla with the chicken mixture, roll tightly, and place seam-side down in a small baking dish.
Pour the remaining red sauce over the tortillas and sprinkle with shredded cheddar cheese.
Bake for 15 minutes until the cheese is melted and the sauce is bubbly.
Garnish with fresh cilantro and the remaining diced onions before serving.