Cook gluten-free pasta per directions on the box. In the last minute add spinach. Drain and set aside.
Boil cauliflower florets in a pot for 6 minutes or until soft, then drain but reserve ½ cup of cauliflower water.
Melt butter in a skillet over low heat. Stir in mustard then bread crumbs. Stir as they toast to a golden color (about 5 minutes). Set aside.
Add the parmesan, cream and lemon peel to the pasta pot. Stir contents over low heat until pasta is covered.
Transfer pasta mixture to a serving dish and top with bread crumbs. Of course, you are welcome to add more parmesan.