Trim the woody ends and cut the broccoli rabe into 2-inch pieces; halve thick stems lengthwise.
Bring a large pot with a few inches of water to a rolling boil. Season with salt and add the broccoli rabe. Par-boil for 2-3 minutes to cook out the bitterness, then cold shock in icy cold water; drain well. Fill the pot back up with water for the pasta and return to the stove to bring to a boil.
Heat a large skillet over medium heat and melt the anchovies into the oil. Stir in the onion, garlic, sweet peppers and chilies and stir for 3-4 minutes to soften. Add the chopped broccoli rabe and season with salt, to taste, and a little nutmeg. Add the stock and reduce the heat to keep warm.
Season the pasta water with salt; add the pasta and cook to al dente. Add a ladle of starchy cooking water to the broccoli rabe and drain the pasta. Toss with the broccoli rabe and adjust the seasoning. Add the pickled peppers, if using, and a splash of brine. Top with Pecorino and serve.