Make the Smoky Shiitake 'Bacon': Preheat the oven to 375°F. On a large rimmed baking sheet, toss the mushrooms with the olive oil and salt. Arrange the mushrooms in a single layer. Bake on the middle rack of the oven, turning occasionally with a spatula, until lightly browned and very crisp, 20 to 30 minutes.

Remove the mushrooms from the oven and toss with the smoked paprika and garlic powder; season with salt to taste. Store in an airtight container at room temperature for up to three days.

Make the Mac and 'Cheese': Preheat the oven to 400°F. On a small rimmed baking sheet, toss the squash with the olive oil; season with the pepper and ¼ teaspoon of the salt. Roast, turning occasionally with a spatula, until fork-tender, about 30 minutes.

Bring a large pot of heavily salted water to a boil over high heat. Add the macaroni and cook to al dente according to the package directions. Drain the pasta and return it to the pot, off the heat.

In a blender, combine the butternut squash, 2 cups water, cashews, garlic, rosemary and remaining 2 teaspoons salt. Blend on high speed for about 2 minutes, until very smooth. Add the sauce to the pot with the pasta and toss to coat. Taste and adjust the seasoning. If the sauce is too thick, add water, 1 tablespoon at a time, until the desired consistency is reached. Top each serving with smoky shiitake 'bacon' and dust with smoked paprika.