Spinach Parmesan Custard with Frico

1. Cook onion in butter, covered, in a 6- to 8-quart heavy pot over moderately low heat, stirring occasionally, until softened, about 10 minutes. Add spinach and water and cook, covered, over moderately high heat, stirring occasionally, until just wilted, about 4 minutes. Drain in a large sieve set over a bowl, pressing on spinach. (Discard liquid.)
2. Preheat oven to 350 degrees F. Lightly oil springform pan.
3. Whisk together eggs, milk, cheese, salt, pepper, and nutmeg in a large bowl, then stir in spinach.
4. Spoon into springform pan, spreading evenly, and bake until custard is set and no longer wet in center, 50 to 55 minutes. Cool 10 minutes in pan on a rack, then run a sharp knife around edge to loosen and remove side of pan. Cut into 8 wedges and serve warm or at room temperature.

Yield: 8 servings