In a large skillet, sauté the garlic in the olive oil until golden. Remove the garlic. If using pancetta, add it and sauté until light golden. Add the cauliflower and then enough water to almost cover it. Cook, covered for 5-10 minutes, then uncovered for another 5 minutes until water is mostly evaporated. The cauliflower should be tender, but not mushy. Add about 1 teaspoon each of salt, black pepper and/or crushed red pepper, depending on your taste.
Bring a large pot of salted water to a boil.
Cook the pasta until very al dente (about 3-4 minutes less than the package’s instructions) and drain it. Place the pasta into an oven proof casserole. Mix in the cauliflower, add the cream if you are using it, and then sprinkle the cheese and breadcrumbs evenly across the top. Add a few small pats of butter. Place under the broiler for 5-10 minutes until the cheese is melted and golden brown. Serve immediately.