- 2 1/2 cups whole milk
- 5 tablespoon butter
- 1/4 cup all purpose flour
- 4 large eggs, separated
- 1 cup shopped shallots (about 6 ounces)
- 1 10-ounce package frozen chopped spinach, thawed, drained, squeezed dry
- 2 cups (packed) grated smoked Gouda cheese (about 7 ounces)
- 3/4 teaspoon salt
- 1/2 teaspoon ground black pepper
- 1/2 teaspoon ground nutmeg
- Preheat oven to 350°F. Butter 11 x 7 x 2-inch glass baking dish. Bring milk to boil in medium saucepan. Remove from heat. Melt 4 tablespoons butter in heavy medium saucepan over low heat. Add flour; stir 3 minutes. Gradually whisk in warm milk. Increase heat to medium; whisk constantly until mixture is thick and smooth, about 4 minutes. Remove sauce from heat. Whisk in yolks. Cool slightly.
- Melt 1 tablespoon butter in large skillet over medium heat. Add shallots; sauté until tender, about 3 minutes. Transfer to large bowl. Mix in sauce, spinach, 1 1/3 cups cheese, salt, pepper and nutmeg. (Can be made 2 hours ahead. Cover and let stand at room temperature. Stir over low heat until just lukewarm before continuing.)
- Using electric mixer, beat egg whites in large bowl until stiff but not dry. fold whites into spinach mixture in 2 additions. Transfer to prepared baking dish. Sprinkle remaining 2/3 cup cheese over. Bake until puffed and set about 45 minutes