3 pounds fresh spinach
3 1/2 to 4 1/2 tablespoons unsalted butter
Salt and pepper
1 1/2 tablespoons flour
1 cup stock or cream
3/4 cup grated Swiss cheese
2 tablespoons fine, dry breadcrumbs
Stem and wash your spinach well but no need to spin or pat it dry. Place spinach in a large pot over high heat. Cook, covered, with just the water clinging to leaves, stirring occasionally, until wilted, about 2 to 4 minutes for baby spinach and 4 to 6 minutes for regular spinach. Transfer to a colander, immediately fill pot with cold water, transfer it back to the pot of cold water to shock it (stop the cooking) and drain again. Squeeze a small amount of the spinach at a time in your hands to extract as much water as possible. Chop the spinach coarsely. You should have about 3 cups of chopped spinach, or about 1 cup per pound.
Wipe out pot then melt 2 tablespoons butter over moderately high heat and stir in the spinach. Cook for 2 to 3 minutes or until all of the moisture from the spinach has boiled off — you’ll know you’re done when the spinach begins to stick to the pan.
Lower the heat and sprinkle with flour and stir for 2 minutes to cook the flour. Add 2/3 of your stock or cream, a tiny bit at a time, scraping up any stuck spinach as you do. Once the liquid is added, simmer for another minute or two, stirring frequently to prevent sticking. If you’re feeling especially indulgent, stir in one more tablespoon of butter. If needed, add all or part of remaining liquid. Season with salt (I found 1/2 teaspoon table salt about right) and pepper.
Preheat oven to 375 degrees. Lightly butter a shallow 1-quart baking dish. Stir 1/2 cup cheese into the spinach and pour it into the baking dish. Mix the remaining cheese with breadcrumbs and sprinkle on spinach. Melt 1 1/2 tablespoons remaining butter and pour it over the top. Bake until heated through and slightly brown on the top, about 30 minutes.