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

In a large skillet, heat olive oil over medium heat. Add diced onion and a pinch of salt, cooking until softened.

Stir in minced garlic, chili powder, and ground cumin, cooking for an additional minute.

Add cooked shredded chicken to the skillet, stirring to combine and heat through for 2-3 minutes.

In another bowl, mix salsa verde with sour cream until smooth.

Layer one-third of the salsa verde mixture in the casserole dish, followed by half of the corn tortillas, half of the chicken mixture, and one cup of cheese. Repeat the layers.

Bake in the preheated oven for 15-20 minutes, until the cheese is melted and bubbly.

Allow to cool for a few minutes before serving. Top with cilantro, Cotija cheese, jalapenos, or red onion as desired.