Preheat oven to 350 degrees. Grease an approximately 8″ x 8″ or 2 quart baking dish (or spray with cooking spray. Set aside.
Add olive oil to a large skillet. Drop in diced onion, season with salt, black pepper, garlic powder and cumin. Cook 2-3 minutes stirring occasionally or until onions are tender.
Transfer half of the onions to a large bowl. To the same skillet with the onions, pour in salsa verde and cilantro. Stir to combine. Simmer 3-4 minutes then set aside.
Add shredded chicken to same large bowl with the onion. Add sour cream, half of the cheese and 2 tablespoons of the reserved salsa verde sauce.
Divide chicken mixture between the tortillas, roll and place place seam side down in the baking dish. Pour remaining salsa verde sauce over the top of the enchilada and sprinkle on the rest of the cheese.
Bake uncovered 20 minutes or until hot and the cheese is melty. Optional: broil last 1-2 minutes to lightly brown the top. Garnish with fresh cilantro and enjoy right away.