Serves 6 as a first course.
2 10-oz packages frozen chopped spinach, thawed and squeezed to remove as much water as possible
2 large eggs
1 cup heavy cream
Kosher salt and fresh black pepper to taste
1/2 tsp freshly grated nutmeg
1 cup Parmigiano-Reggiano cheese, coarsely grated
1/2 cup golden raisins
Combine thawed, squeezed spinach in a bowl with the cream, eggs, 1/2 cup grated cheese, raisins, nutmeg, salt and pepper to taste. Mix well to break up the spinach. Adjust seasoning; the mixture should be slightly salty. Store in the refrigerator for a few hours or overnight so the spinach and raisins can absorb the cream and the flavors can mellow.
Preheat oven to 350°F.
Fill the pre-baked tart shell (or pie crust) with spinach filling, and smooth out to level. The filling should not be more than 1/3-inch thick. Sprinkle with remaining cheese and bake until set and golden. Let cool slightly or to room temperature, and cut into wedges.