*To make preparation easier, cook the butternut squash a day or two in advance. To cook the squash, preheat oven to 375ºF. Place whole squash in a casserole dish or on a parchment lined baking tray. Roast for about 45 minutes, or until a sharp knife can be easily inserted. Remove from oven and let cool. When cool, cut squash open and scrape out flesh into a bowl which can be sealed until ready to use.
Bring a large pot of salted water to a boil. Add macaroni and cook according to package directions. Strain and set aside in the pot.
Preheat the oven to 350ºF. Lightly oil a large casserole dish. Heat 2 tablespoons vegan butter in a large pan over medium heat. Add onions, celery, and a pinch of salt. Cook for about 10 minutes, until vegetables are soft and translucent, being careful not to brown them. Empty into a small bowl and set aside.
To make the roux, melt remaining 2 tablespoons of vegan butter in the pan. Sprinkle in flour and whisk together. Cook for a couple of minutes while mixture is bubbling and begins to thicken. Whisk in non-dairy milk, and cook for a couple minutes more. Remove skillet from heat.
In a blender or food processor, add the roux, onion-celery mixture, cooked squash, hot sauce, nutritional yeast, onion powder, garlic powder, and about a teaspoon of salt. Puree till smooth.
Pour the squash mixture over the cooked macaroni in the pot. Stir to combine. Taste and season with salt or more hot sauce. Pour the macaroni mixture into the prepared casserole dish. Sprinkle corn chip crumbs on top of the mac ‘n’ cheese. Bake until bubbly and brown, 30 to 35 minutes. Remove from oven and let sit for 5 minutes before serving.
