Cook cauliflower in a large saucepan of boiling salted water for 5-8 minutes or until just tender. Remove with a slotted spoon and, when cool enough, mash with a potatoes masher. Reserve cooking water.
Heat oil in another saucepan over medium heat. Add garlic and stir for 3-5 minutes or until disintegrated. Add cauliflower, salt and pepper and gently toss to coat and heat through.
Meanwhile, bring reserved cooking water to the boil over medium heat and cook pasta until al dente. Drain, reserving 1 cup pasta water. Return pasta to pan then add cauliflower mixture, pecorino and enough reserved pasta water to moisten. Toss well to combine then serve immediately, scattered with extra pecorino and pepper.