Preheat oven to 350 degrees F (175 degrees C). Spray a 9x13-inch baking dish with cooking spray.
Combine cauliflower, potatoes, and water in a large microwave-safe bowl. Cover and cook in microwave on high for 4 minutes. Drain well.
Stir cream of chicken soup, mayonnaise, coconut milk, jalapeno pepper, and curry powder together in a bowl; season with salt and pepper. Add drained cauliflower and potatoes to cream of chicken soup mixture; mix well and pour into prepared baking dish. Sprinkle bread crumbs and almonds over vegetables and drizzle with butter.
Bake in the preheated oven until bubbly and lightly browned, about 50 minutes. Allow casserole to rest for 10 minutes before serving.