2leeks, (white and light green parts only), chopped
3/4teaspoonpepper
1/2 teaspoonsalt
1/4teaspoonnutmeg
1/3cupall-purpose flour
3cupsmilk
1cupParmesan cheese, grated
1tablespoonDijon mustard
1/2cup bread crumbs, coarse fresh
Instructions
In a large pot of boiling water, blanch the spinach in batches, until it is wilted, about 20 seconds. With a slotted spoon, transfer the spinach to a bowl of ice water. Drain and press out the water. Chop the spinach and set it aside.
Preheat the oven to 375°F.
In a saucepan, melt the butter over medium heat. Cook the leeks, salt, pepper and nutmeg, stirring occasionally, until softened, about 10 minutes. Sprinkle the leek mixture with flour and cook, stirring, for 2 minutes. Whisk in the milk. Cook, stirring often until it is thick enough to coat the back of a spoon, about 8 minutes.
Add the spinach, 3/4 cup of cheese and the mustard. Cook, stirring until hot.
Scrape the mixture into an 8 inch square glass baking dish or gratin dish. Sprinkle with bread crumbs and the remaining cheese. Bake in a 375°F oven until the top is crisp and golden, about 25 minutes.
Makes 8 servings.
Notes
To make this spinach casserole ahead: After adding the remaining cheese, let it all cool. Cover your dish with foil and refrigerate for up to 24 hours. Bake the casserole for 15 minutes longer.