Preheat the oven to 425 degrees F. Cut the cauliflower into 1/2-inch pieces and toss with 2 tablespoons of the oil, 1 teaspoon salt and 1/2 teaspoon pepper. Spread on a baking sheet and roast until golden, about 45 minutes.
Combine the broth and 1 cup water in a saucepan and bring to a bare simmer.
Heat the remaining 3 tablespoons oil in a medium, heavy pot over medium-high heat until hot. Add the garlic, onions, 1 teaspoon salt and 1/2 teaspoon pepper, and cook until softened, about 8 minutes. Stir in the oats and wine, and boil until the liquid is reduced by half, about 2 minutes.
Stir in the simmering broth 1 cup at a time, adding more after half of the liquid has evaporated. Continue stirring until the oats are tender, 35 to 40 minutes. Use all of the broth. Stir in the butter, cheese and parsley and season with salt and pepper.
Serve immediately, topped with the roasted cauliflower and parsley.
From Food Network Kitchens