I have heard of gratins before with potato or other veggies but spinach gratin was new to me. I came across this recipe after my parents told me to use up the 2.5 pound bag of spinach in our fridge. This was perfect because it called for a LOT of spinach and we had everything else in our kitchen. It was almost liked a creamed spinach dish but with milk instead of heavy cream. The panko on the top added a great bite of crunch to the dish. I cannot praise this dish enough. It was so simple and so delicious. This is a must have side dish for any dinner and you will go back for more and more spoonfuls until there is no more left.
What you need:
4 tablespoons unsalted butter
2 medium-sized yellow onions, chopped
1/4 cup unbleached flour
3 cups organic whole milk
1/4 teaspoon freshly grated nutmeg
pinches of cayenne
1 and 1/2 cups grated Gruyere cheese
3 16 oz. bags of organic, chopped spinach - thawed
1/2 to 1 teaspoons kosher salt
1/4 to 1/2 teaspoons ground white pepper
Preheat oven to 400 degrees.
Squeeze the liquid from the thawed spinach, handful by handful. Set aside.
Heat milk to simmer in saucepan.
Melt the butter in a heavy-bottomed pot. Add onions and cook until wilted but not browned, about 10 minutes. Add the flour and cook for 2 minutes. Stir in the hot milk and whisk the sauce until it thickens. Add the nutmeg and cayenne. Turn off the heat.
Stir in the cheese and season with salt and pepper. Taste and correct seasoning. Add the spinach and mix in well.
Pour into a 9X11 glass or ceramic baking dish.* Prepare crumb topping.
Melt butter in medium skillet. Add panko, sprinkle with sea salt and stir until lightly toasted. This occurs quite suddenly.
Gently smooth the toasted panko on top of the gratin. Cook for 30-35 minutes until bubbling.
* I halved the recipe and put it in a smaller dish (pictured above)
Recipe from: Food52