Preheat your oven to 350°F (175°C).
In a skillet, heat olive oil over medium heat and sauté diced onions until translucent.
Add shredded chicken, chili powder, salt, and pepper to the skillet and mix well.
Warm the tortillas in a microwave for 30 seconds to make them pliable.
Spread a tablespoon of enchilada sauce in the bottom of a baking dish.
Place a small amount of the chicken mixture in each tortilla and roll them up tightly.
Lay the rolled tortillas seam-side down in the baking dish.
Pour the remaining enchilada sauce over the tortillas.
Sprinkle shredded cheese on top of the sauce.
Bake in the oven for 20-25 minutes until the cheese is bubbly and golden.