Arrange oven rack in upper third of oven. Preheat broiler.
In a large broiler-proof skillet heat oil over medium-high heat. Add beef, onions, Italian seasoning and salt. Cook, crumbling with a wooden spoon until beef is browned and onion is tender, 6 to 8 minutes. Drain fat.
Sprinkle the flour over the beef mixture and stir to coat. Add broth and corn. Cook and stir until mixture simmers and thickens, about 3 minutes. Spread the cauliflower puree over the beef mixture. Top with Parmesan. Broil until the topping is golden and hot, about 6 minutes.
Steam cauliflower florets until tender, about 14 minutes. Puree in a food processor with half and half, and salt and pepper to taste. Freeze half.