Bring a large pot of water to a boil. Prepare an ice-water bath; set aside. Add salt and broccoli rabe to the boiling water. Cook until just tender. Drain, and transfer to ice bath. When cool, drain, and set aside.
Heat oil in a 10-inch skillet over medium-high heat. Add garlic and shallots; cook until just golden. Add sausage; saute, breaking up with the back of a spoon, until cooked through. Add broccoli rabe and stock. Cook until heated through.
Into the same large pot, add pasta; cook according to package directions until al dente. Drain.
Add pasta to skillet; toss to combine. Season with salt, black pepper, and crushed red pepper. Sprinkle with cheese; toss to combine. Serve immediately.