1. Preheat oven to 375°F (190°C) and grease a 9×13-inch casserole dish.

2. Slice zucchini into thin half moons and pat dry with paper towels.

3. In a skillet, sauté zucchini with a little butter, salt, and garlic powder until slightly softened, then set aside.

4. Shred the rotisserie chicken and season with salt, pepper, and dried thyme.

5. In a large bowl, whisk together cream of chicken soup, sour cream, milk, and half of the shredded cheeses until smooth.

6. Spread a thin layer of sauce in the bottom of the dish, then layer zucchini, chicken, sauce, and cheese, repeating until ingredients are used.

7. Combine panko breadcrumbs with melted butter and sprinkle evenly over the top, then finish with remaining cheese.

8. Bake uncovered for 30 to 35 minutes, until the top is golden and the edges are bubbling.

9. Let the casserole rest for 10 minutes before serving to allow layers to set.