Preheat your oven to 375°F (190°C) and lightly grease a 9x12-inch casserole dish.

In a large skillet, heat olive oil over medium heat. Add chopped onion and sauté for about 5 minutes until softened and golden.

Stir in minced garlic, chili powder, and cumin. Cook for an additional minute, allowing the spices to bloom.

Add shredded chicken to the skillet and mix well. Cook for 2-3 minutes until heated through, then remove from heat.

In a separate bowl, combine salsa verde and sour cream. Stir until smooth and well incorporated.

Spread ¾ cup of the salsa mixture on the bottom of the greased casserole dish. Arrange half of the tortillas over the sauce.

Layer half of the chicken mixture over the tortillas, then drizzle with 1 cup of the remaining salsa mixture. Sprinkle ½ cup of Monterey Jack cheese over this layer.

Repeat layers with the remaining tortillas, chicken, and another drizzle of salsa, topping with remaining cheese.

Bake for 15-20 minutes until the cheese is melted and bubbly with a slight golden hue.

Let it cool for 10-15 minutes before serving to allow it to set properly.