Cook the broccoflower florets in a large pot of salted water until they are very soft. Drain and reserve some of the cooking liquid. Pulse in a processor until almost pureed, adding cooking liquid if needed. Set aside.
Cook the broccoli florets in salted water until very soft. Remove with a slotted spoon and transfer to a blender or processor and process until pureed. Add enough cooking liquid, as needed, for smoothness and liquidity.
Combine the two purees. Warm them over low heat in large saute pan with stock and olive oil. Season with salt and pepper.
Cook the pasta until tender. Toss with broccoli sauce. Top each portion with toasted pine nuts, a grinding of black pepper and grated pecorino cheese.
