Cook cauliflower and butternut squash until tender. (There are various methods of doing this, I used my crock pot, but you could also boil the cauliflower for about 15 minutes, and bake the squash in the oven at 325 for 45-50 minutes. Or you could microwave the cauliflower in a microwave safe dish with a small amount of water for 10 minutes, and microwave the squash for 10 minutes as well.)
Once tender, peel the butternut squash, and cut in half lengthwise, and remove seeds. Place cauliflower in blender with 2 tbs milk, 2 tbs parmesan cheese, 1/2 tsp garlic powder, and salt and pepper to taste. Blend until smooth. Spoon into serving dish.
Place squash in the blender with 2 tbs milk, 2 tbs parmesan cheese, 1/2 tsp garlic powder, and salt and pepper to taste. Blend until smooth. Pour into serving dish with cauliflower, and mix just until swirled. Serve warm with light butter or additional parmesan cheese if desired.