Preheat the oven to 350°F (175°C) and lightly spray a 9 x 13-inch baking dish with cooking spray.
Cook the rice according to package directions, substituting 1 cup of the coconut milk for 1 cup of water called for.
In a large mixing bowl, combine the cooked rice with the remaining coconut milk, cream of chicken soup, drained pineapple chunks, drained and diced water chestnuts, cooked chicken, sliced green onions, sliced almonds, and half of the shredded cheddar cheese. Stir until evenly combined.
Spread the mixture into the prepared baking dish in an even layer.
Bake uncovered for 30 minutes.
Remove the casserole from the oven, sprinkle the remaining shredded cheddar cheese and the chow mein noodles evenly over the top, then return to the oven and bake an additional 8–10 minutes, until the cheese is melted.
Let the casserole sit a few minutes, then serve immediately.