Step 1

Soak the dried porcini mushrooms for 60–90 minutes, reserving the water. See Chef’s Notes.

Step 2

Cook the pasta: Add the porcini water that you reserved as part of the pasta water and cook the pasta according to directions. Also, when draining the pasta, reserve one cup of the pasta water. Set aside the pasta and the reserved one cup of water.

Step 3

Make the Porcini Cashew Butter: Heat a medium stove-top pan on medium-high heat.

Step 4

Once hot, add the shallots and continuously stir for 30–60 seconds.

Step 5

Deglaze the pan with 2–4 tablespoons of water and turn the heat down to medium.

Step 6

Add the garlic and mushrooms and cook for 60 seconds. Add more water to prevent sticking, if needed.

Step 7

Add the vegetable broth and cashews and bring to a simmer for 10 minutes, stirring occasionally. The liquid will reduce by about 25 percent.

Step 8

Add the cashew mushroom mixture and salt, if using, to a blender or food processor. Blend until smooth. Set aside.

Step 9

Add the one cup of the pasta cooking liquid to the stovetop pan you used for the mushrooms, heating on medium heat. Add the cooked pasta followed by the spinach and cook until the spinach is tender, about 1 minute. Stir in the sauce until everything is warmed through. If the sauce is too thick, add 1–2 tablespoons of water or vegetable broth until you reach the desired consistency.

Step 10

Divide between plates and top with freshly ground peppercorns and crushed red pepper flakes, if desired.