If making with mushrooms:
12 to 16 ounces hen-of-the-woods/maitake mushrooms, pulled into bite-sized pieces
2 large shallots, peeled and thinly sliced lengthwise
Non-aerosol cooking spray
Salt and pepper
If making with radicchio:
Large head of radicchio or Treviso, quartered, cored and thinly sliced
Zest of 1 lemon, thinly slice peel (white pith removed) into small matchsticks
For the Spaghetti alla Gricia:
⅓ to ½ pound guanciale or pancetta
1 tablespoon extra-virgin olive oil (EVOO)
1 pound spaghetti
4 cloves garlic, chopped or sliced
1 cup grated Parmigiano-Reggiano cheese or Pecorino cheese or a combination of both
Black or red pepper, to taste
Preheat oven to 475°F. Arrange mushrooms and shallots on a parchment-lined baking sheet. Spray to coat or toss with oil, season with salt and pepper, and roast at center oven to crispy 15 minutes.
Bring water to a boil for pasta.
Place the guanciale in the freezer for 10 minutes. Once it's firm, slice it into thin ½-inch-long pieces.
Heat a large skillet over medium-high heat. Add EVOO, a turn of the pan, add guanciale or pancetta and render slowly over 7 to 8 minutes, reducing heat if necessary. You want all the flavor and a lightly browned product.
Salt the boiling water, drop the pasta and cook 6 to 7 minutes.
Add garlic to guanciale and swirl. Add 1 cup cooking water to pan.
Add radicchio (if using) to pan to wilt and add the lemon zest, pasta and cheese to toss and emulsify.
Serve pasta in shallow bowls and, if using, top with mushrooms and shallots.