Preheat oven to 375°F (190°C).

Heat olive oil in a large skillet over medium heat.

Add onion and cook until softened.

Stir in cooked, shredded chicken and salsa.

Add diced tomatoes and garlic powder.

Simmer for 10 minutes.

Lightly fry each tortilla in oil or heat in a microwave to make pliable.

In a 9x13 inch baking dish, layer tortillas, chicken mixture, cheese, and black olives.

Repeat layers until all ingredients are used, ending with a layer of cheese.

Bake for 30-40 minutes, or until golden brown and bubbly.

Let stand for 10 minutes before serving.