Preheat oven to 425°F.
Cut end off the bulb of garlic to expose the cloves. Coat the garlic with a drizzle of EVOO and top with rosemary, salt and pepper. Wrap in a foil pouch and roast 35-40 minutes until very soft. Let cool to handle then squish the garlic cloves from their skins and paste in a small bowl with the rosemary.
While the garlic cooks, place wine, chicken or vegetable stock, about 1/4 cup EVOO, about 1 tablespoon salt, lemon juice, butter, chili flakes and bay leaves in a pot. Bring to a boil, add the whole cauliflower and partially cover. Reduce heat a bit and cook 15 minutes to soften. With a spider or 2 spatulas, remove the cauliflower to a rimmed baking sheet and season with a little freshly grated nutmeg. Brush with some poaching liquid and sprinkle with the Parmigiano. Reserve 1/2 cup of the liquid for sauce (Note:
Raise oven heat to 475°F and place cauliflower in center of oven.
Roast the cauliflower for about 30 minutes until deeply golden in color, drizzle with a touch more EVOO and season with flaky sea salt.
While the cauliflower is roasting, mix the ricotta with the rosemary-roasted garlic paste, the reserved 1/2 cup poaching liquid, 1/4 cup milk and a small handful of Parm. Mix until fairly smooth and place in serving boat or small dish for passing at table.
Cut the cauliflower into large florets at the tables and pass with sauce.
If you are preparing mashed potatoes, this liquid is a delicious addition as well. It can also be used as cooking liquid for rice dishes.
For mashed potatoes, peel and cube 1 Russet potato per person, start in cold water and bring to a boil. Add salt and cook to tender, drain and place in hot pot. Mash with cauliflower poaching liquid or warm milk and Boursin cheese. Season with salt and pepper to taste and minced chives for garnish.