Fit a large pot or Dutch oven with a steamer basket. Add 1 ½ inches of water to the pot and bring it to a boil over medium-high heat. Add the butternut squash to the basket, cover, and steam for 15 minutes or until very tender.

Preheat oven or toaster oven to 350°. Pour the panko bread crumbs into a baking dish, and toast for 7 minutes, or until golden. Set aside for topping the finished mac & cheese.

Whisk the arrowroot powder and ⅓ cup of the milk in a small mixing bowl until smooth. Set aside.

Warm a saucepan over medium heat. Add the oil or vegan butter and heat until melted. Add the minced garlic and sauté for 1-2 minutes, until just golden.

Add the remaining soy milk, Dijon mustard, onion powder, lemon juice, nutritional yeast, and salt to the saucepan. Whisk to combine.

Whisk the arrowroot milk mixture into the saucepan. Cook over medium-low heat, whisking regularly, for 3 minutes or until thickened.

Cook the pasta following the package directions until al dente, or still slightly chewy. Drain the noodles.

Transfer the sauce to a blender and add the butternut squash. Blend until smooth and season with more nutritional yeast and salt to taste. The sauce should be pretty salty to balance the noodles.

Pour the cheese sauce over the noodles and stir well to coat. Enjoy hot!

Garnish with the toasted panko bread crumbs and fresh parsley.