Here it is!
5C coarsely chopped cauliflower (1/2 medium head)
2-1/2t salt, divided
1T unsalted butter
1/4t white pepper
3 eggs, lightly beaten
1/2 oz. finely grated Parmesan (1/4C) -- use small holes in box grater
Put oven rack in center and heat to 350. Butter a 1-qt. soufflé dish, then line bottom with parchment or wax paper and butter the paper. Chill dish until ready to fill.
Cook cauliflower with 2t salt in 3-4-qt. pot of boiling water, uncovered, until tender, 15-18 minutes. Drain well then puree in processor until smooth.
Melt butter in 1-qt. saucepan over medium-low heat. Add flour and cook, whisking, 2 minutes. Add milk in a stream, whisking, then add pepper, nutmeg and remaining 1/2t salt, whisking. Bring to boil over medium heat, whisking, then reduce heat and simmer, whisking constantly, 2 minutes. Remove from heat and cool the béchamel 5 minutes.
Whisk cauliflower puree into béchamel, then add beaten eggs, whisking until combined well. Transfer to soufflé dish and put dish in 13x9 pan, then add enough boiling water to reach halfway up the side of soufflé dish.
Bake until center is firm to touch and mousse begins to pull away from side of dish, 35-40 minutes. Remove mousse from oven and water bath. Position rack so that top of mousse with be 4-6 inches from broiler, then preheat broiler. Run knife around edge of soufflé dish, then place an ovenproof platter on top of dish and invert mousse onto platter. Sprinkle cheese evenly over top and broil until melted and golden brown, about 2 minutes.
I have adapted the joy of cooking souffle recipe to great success. A friend makes cauliflower baked with queso fresco and roasted and skinned jalapenos which I have adapted into a souffle. I make my joy of cooking bechamel. I steam cauliflower until slightly softer than usual. I chop it finely with roasted and skinned jalapenos (to taste, of course). Come summer, I will serve this with a roasted corn salsa, and an avocado rich salad.
I have also made this for christmas dinner and used gruyere and withheld the peppers. Everybody loved it.