Preheat your oven to 350F. Lightly grease a 9x13 casserole dish.
Bring a large pot of water to a boil and cook macaroni as per the directions on the package. When finished cooking, strain and run under cold water immediately to prevent from overcooking.
Add milk, cornstarch, garlic powder, nutritional yeast, dijon mustard, and steamed butternut squash to your blender. Blend on high for 30 seconds until all mixed and uniform. Add in salt and pepper to taste.
Pour the sauce over the macaroni and mix well.
Place half the macaroni in a greased 9x13 casserole dish.
Layer with half the mozzarella cheese.
Add the remainder of the macaroni. Cover with the remainder of mozzarella cheese.
Bake at 350F uncovered for 30 minutes. Until cheese is melted and golden brown.
Portion pan into 9 servings and enjoy!