Preheat the oven to 375°F and grease a 9x12 casserole baking dish.
Heat olive oil in a large skillet over medium heat. Once heated, add in the onion and salt and cook until softened.
Stir in the garlic, chili powder, and cumin and cook for another minute before adding in the chicken. Mix well and remove from heat.
In a large bowl, combine the salsa Verde and sour cream and stir well.
Layer ¾ cup of the salsa verde mixture on the bottom of the casserole dish.
Top with 5 tortilla halves.
Layer on half of the chicken mixture, 1 cup of salsa verde, and ½ cup cheese. Repeat with another round of 5 tortilla halves, the remaining chicken, 1 cup salsa verde, and ½ cup cheese.
Finish with a final layer of 5 tortilla halves, the remaining salsa verde, and the remaining cheese.
Bake for 15-20 minutes until the cheese has melted and the sauce is bubbling.
Complete by adding on your favourite toppings and serve.