Preheat oven to 350 degrees.

Prepare the macaroni according to the package directions.

Drain the cooked macaroni and set aside.

Combine the diced potatoes, carrot, onion, and water in a saucepan over medium heat.

Bring to a boil, then reduce the heat, cover, and simmer for 10 minutes, or until the vegetables are tender.

Put the vegetable oil, cashews, macadamia nuts, salt, garlic, mustard, lemon juice, black pepper, cayenne, cooked vegetables, and their cooking water into a blender.

Process until completely smooth, creating the "cheeze" sauce.

Toss the cooked pasta with the sauce until completely coated.

Transfer macaroni and sauce to a lightly oiled 3-quart casserole dish.

Sprinkle with the bread crumbs, if using.

Bake for 30 minutes or until bubbling and golden brown.