Break cauliflower into florets, discarding core and leaves. Rinse florets.
In a 4- to 5-quart pan over high heat, bring about 3 quarts water to a boil. Add cauliflower and cook until just tender when pierced, 5 to 8 minutes.
Drain cauliflower and arrange in a shallow 1 1/2-quart casserole.
Add cream to the empty pan and boil over high heat until it's reduced to 1/2 cup, stirring often, about 5 minutes.
Drizzle cream over cauliflower, sprinkle with pepper, and cover evenly with cheese.
Bake in a 425° oven just until cheese is lightly browned, 4 to 6 minutes. Add salt to taste.