Preheat your oven to 375°F (190°C). Lightly grease a 9x13 baking dish. If not using pre-cooked chicken, cook and shred 1.5 lbs boneless chicken breast.

In a large bowl, combine 3 cups shredded chicken, 1 can diced green chiles, 1 cup shredded Monterey Jack cheese, and 1 Tablespoon taco seasoning. Stir in optional 1/2 cup cottage cheese or Greek yogurt for extra protein.

In a medium saucepan, melt 2 Tablespoons butter over medium heat. Whisk in 2 Tablespoons flour and cook for 1 minute until a paste forms.

Gradually whisk in 2 cups chicken broth and 1 cup milk. Bring to a simmer and cook 3-5 minutes until thickened. Remove from heat.

Whisk in 1 cup Greek yogurt until smooth. Stir in 1/2 teaspoon garlic powder, 1/2 teaspoon onion powder, 1/2 teaspoon cumin, 1/4 teaspoon salt, and a pinch of pepper. Adjust salt to taste.

Pour 1/2 cup sauce into the baking dish. Fill each tortilla with about 1/4 cup filling, roll tightly, and place seam-side down in the dish.

Pour remaining sauce over enchiladas and sprinkle with 1 cup extra cheese. Bake covered for 20 minutes, then uncover and bake 5-10 minutes until bubbly.

Let rest 5 minutes. Garnish with cilantro and olives. Serve warm.