Butter, for baking dish
3 packages (10 ounces each) frozen chopped spinach, thawed and squeezed dry
1 1/2 cups half-and-half
3 large eggs, lightly beaten
1 1/2 cups coarsely grated Gruyere cheese (about 6 ounces)
Coarse salt and ground pepper
1/4 teaspoon ground nutmeg
Preheat oven to 350 degrees. Butter a shallow 1-quart baking dish.
In a large bowl, combine spinach, half-and-half, eggs, 1 cup Gruyere, 2 teaspoons salt, 1/8 teaspoon pepper, and nutmeg; stir to combine. Spread evenly in prepared baking dish, and top with remaining 1/2 cup Gruyere. Bake until set and top is golden brown, 30 to 35 minutes.