Preheat the oven to 350°F (175°C).
In a skillet, heat olive oil over medium heat.
Add diced onions and sauté until translucent.
Stir in the shredded chicken, garlic powder, and cumin.
Warm the tortillas until pliable.
Fill each tortilla with the chicken mixture and roll tightly.
Place rolled tortillas in a baking dish.
Pour remaining white sauce over the tortillas.
Sprinkle shredded cheese on top.
Bake for 20 minutes or until bubbly.