Preheat oven to 375°F. Lightly oil an 8-by-8-inch casserole dish or 9-inch pie pan with olive oil or butter. Spread onions evenly in the dish and place in the oven while you prepare the other ingredients.
In a small bowl, beat eggs, salt free seasoning and milk with a whisk.
Remove dish from oven with mitts and spread cauliflower and cheese evenly. Pour egg mixture over cauliflower, onions and cheese. Sprinkle with paprika.
Bake for 30 minutes, until cauliflower is cooked, and casserole is golden brown.