How to Make It
Preheat the oven to 350°. Grate half of the cauliflower on the large holes of a box grater, stopping when you reach the stems; you should have about 1 cup of grated cauliflower that resembles coarsely grated parmesan. Finely chop the stems and the remaining cauliflower; you should have about 2 cups.
In a saucepan, add the chopped cauliflower, cream, water and 2 tablespoons of the butter; season with salt. Cover and cook over moderate heat until the cauliflower is tender and the liquid is nearly evaporated, 8 minutes. Scrape the mixture into a food processor and puree until very smooth. Wipe out the saucepan and return the puree to it; keep warm.
In a small baking dish, toss the tomatoes with the olive oil. Roast for about 10 minutes, just until the skins begin to burst.
Meanwhile, bring a large saucepan of salted water to a boil. Add the fregola and cook until al dente. Drain the fregola and return it to the pot. Add the vegetable broth, the crushed red pepper and the remaining 2 tablespoons of butter and cook over low heat, stirring until the sauce is creamy. Stir in the grated cauliflower and cook until just tender, about 5 minutes. Stir in the mint.
Spoon the cauliflower puree onto plates. Top with the fregola and roasted tomatoes and serve immediately.