Bring water to a boil in a 2-quart heavy saucepan over moderate heat, then add spinach in handfuls and cook, tossing, until wilted, 2 to 3 minutes. Transfer to a sieve set over a bowl and press on spinach with back of a wooden spoon to remove excess liquid, then discard liquid.
Add cream, garlic, nutmeg, salt, and pepper to saucepan and boil until reduced to 1 tablespoon, about 2 minutes. Discard garlic and add spinach to cream mixture, tossing until coated and heated through.
