Preheat oven to 350°F/180°C.
Prepare elbow pasta according to package directions. Drain in a colander until ready to use.
In a large high speed blender add cashews, onion powder, garlic powder, sea salt and pepper, ground mustard, lime juice, soy sauce, nutritional yeast, paprika, ground nutmeg, and coconut milk.
Blend together for about 3 minutes on a high speed, until sauce is completely smooth and incorporate. If you need to blend longer that's fine, just blend until smooth. Taste and add more salt if necessary.
Add the macaroni to a cast iron skillet or other similarly sized oven safe pot or oven sized container (mine is about 8" to 9"). Pour the sauce over the macaroni. Stir to combine until fully combined and all the macaroni is coated with sauce.
Mix the breadcrumbs, garlic powder, paprika, sea salt and pepper to taste and vegan butter in a small dish with a small whisk or fork until combined. Sprinkle over the top of the Mac and cheese, covering completely.
Bake for 15 minutes until Mac and cheese is set, then broil for a few minutes until top is golden brown.
Remove from oven, allow to cool slightly then serve and enjoy!