Found this one.
Spinach Soufflé
INGREDIENTS:
1 bag (16 oz) frozen chopped spinach
1/4 cup butter or margarine
1/4 cup flour (all-purpose)
1/2 teaspoon salt
1/8 teaspoon ground black pepper
1 cup milk
2 tablespoon very finely chopped onion
1/2 teaspoon salt
1/8 teaspoon ground nutmeg, fresh is best
3 large eggs, separated
1/4 teaspoon cream of tartar
PREPARATION:
Thaw spinach in a colander; squeeze well to get as much moisture as possible out.
Preheat oven to 350°. Butter a 1-quart souffle or casserole dish.
Heat butter in a saucepan over medium low heat. When butter has melted, add flour; stir until smooth and bubbling. Add 1/2 teaspoon salt and 1/8 teaspoon pepper. Gradually add milk, stirring constantly. When mixture is thick and boiling, remove from heat. Stir in the finely chopped onion, 1/2 teaspoon of salt, and the nutmeg.
In a metal or glass mixing bowl, beat egg whites and cream of tartar until stiff peaks have formed. In a separate bowl, beat yolks until frothy and lemon colored.
Stir egg yolks into the sauce mixture; stir in the spinach.
Stir about 1/4 of the beaten egg whites into the spinach mixture, then gently fold in the remaining egg white mixture.
Pour into the prepared souffle dish; set dish in a large pan then add water to a depth of about 1 inch.
Bake for 50 to 60 minutes. The top will be lightly browned. Serve immediately.