Preheat oven to 350°F. Peel, seed and cut squash into thin slices. Peel, core and slice apple into thin slices.
In a glass casserole dish sprayed with Pam, place layer of squash, followed by layer of apples. Sprinkle packet of Sweet-n-Low on apples followed by generous sprinkling of cinnamon. Repeat layers and seasonings ending with layer of squash. Sprinkle final packet of Sweet-n-Low followed by generous sprinkling of cinnamon. Dot with butter slices.
Cover dish and place in oven for approx. 1 - 2 hours until squash is tender and dish is bubbling.