Radicchio Jam Rigatoni

Preparation

1. Step 1

   Cook 4 oz. guanciale (salt-cured pork jowl) or pancetta (Italian bacon), cut into ½" pieces, in a dry medium Dutch oven or other heavy pot over medium-high heat, stirring occasionally, until light golden brown and starting to crisp, about 5 minutes (don’t let pieces get too crunchy). Using a slotted spoon, transfer to a small plate, leaving fat behind.

   Step 2

   Add 2 large sweet onions (such as Vidalia; about 1 lb.), quartered through root ends, thinly sliced crosswise, and a small pinch of kosher salt to same pot (if it looks dry, add up to 2 Tbsp. extra-virgin olive oil) and cook, stirring often, until deep golden brown, 15–18 minutes.

   Step 3

   Set aside a small handful (about ½ cup; eyeballing is fine) of 1 small head of radicchio (about 1 lb.), quartered through root end, cored, cut into 1" pieces for serving and add remaining radicchio to pot. Add 5 garlic cloves, finely chopped, and 2 small sprigs thyme, leaves picked, and cook, stirring often, until radicchio is softened and wilted, 5–8 minutes.

   Step 4

   Reduce heat to medium and add ¼ cup red wine vinegar, 2 Tbsp. sugar, and ½ cup water; cook, stirring occasionally, until liquid is syrupy and onions are very tender, 5–8 minutes.

   Step 5

   Meanwhile, cook 12 oz. rigatoni or other short pasta in a large pot of boiling lightly salted water, stirring occasionally, until very al dente, about 2 minutes less than package directions.

   Step 6

   Using a spider or slotted spoon, transfer pasta to pot with radicchio jam and add 4 Tbsp. unsalted butter and 1 cup pasta cooking liquid. Cook, stirring constantly, until sauce is emulsified. Add 2 oz. Parmesan, finely grated (about 1½ cups), a little at a time, stirring constantly, until cheese is melted and sauce is creamy and clinging to pasta, about 3 minutes. (If the sauce looks very thick, mix in more pasta cooking liquid 1–2 Tbsp. at a time until thinned to the right consistency; you want it on the saucier side as it will thicken as it cools.) Remove pot from heat and add guanciale and reserved raw radicchio; season very generously with freshly ground pepper (about 2 tsp.). Toss to combine, then squeeze juice from lemon wedges over to taste and season with more salt if needed.

   Step 7

   Divide pasta among shallow bowls and drizzle generously with oil.