How to Make It
In a large skillet, heat 3 tablespoons of the olive oil. Add the shallots and cook over moderate heat until softened, about 2 minutes. Add the anchovies, half of the garlic and the crushed red pepper and cook until the anchovies have dissolved, about 1 minute. Add the broccoli rabe stems, half of the leaves and florets and 1 cup of water and cook over high heat until the stems are crisp-tender, about 3 minutes. Transfer to a blender and puree until smooth. Season with salt and black pepper. Wipe out the skillet.
In a large pot of salted boiling water, cook the pasta until al dente. Drain the pasta, return it to the pot and stir in 1 tablespoon of the olive oil.
In the large skillet, heat the remaining 2 tablespoons of olive oil. Add the sausage and cook over moderate heat, breaking up the meat with a spoon, until browned, about 6 minutes. Add the remaining garlic and cook until fragrant, about 30 seconds. Add the clams and wine, cover and cook over moderately high heat, shaking the skillet a few times, until the clams start to open, about 10 minutes. Stir in the remaining broccoli rabe leaves and florets and cook, stirring, until wilted, about 2 minutes. Discard any clams that do not open. Transfer the clam and broccoli rabe mixture to the pot with the pasta, add the broccoli rabe puree and toss to combine. Serve with cheese.