Cook pasta according to package directions, adding cauliflower the last 7 minutes of cooking. Drain. Place 2 cauliflower wedges on each plate. Set pasta aside.
Meanwhile, in a very large skillet cook pancetta over medium heat until crispy. Drain and remove with a slotted spoon and set aside. Add garlic and 1 teaspoon rosemary to skillet and cook for 30 seconds. Add cream and zest to skillet. Bring to a simmer. Simmer, uncovered, for 3 minutes or until slightly thickened; stir in Parmesan. Add pasta to the cream sauce and stir to coat; spoon over cauliflower. Top with pancetta and additional rosemary, if desired.