Graviera or Kefalotyri cheese – 4 cups or 12 oz, grated
White bread – 3 pieces, crusts cut off, torn to small pieces
Shallots – 8, finely chopped
Scallions – 8, cut into 1⁄4″-thick rounds
Baby Spinach – 16 oz, rough chopped
Unsalted Butter – 9 tbsp., melted
Flour – 1/4 cup
Milk – 3 cups
Ground cinnamon – 3/4 tsp.
Grated nutmeg – 1/8 tsp.
Fresh Dill – 1/3 cup, chopped
Extra virgin olive oil – 2 tbsp.
Salt and pepper – to taste
Preparation
Put bread into the bowl of a food processor and pulse until finely ground.
Put bread crumbs and 3 tbsp. butter into a small bowl and combine; set aside. Bring a 6-qt. pot of salted water to a boil.
Add pasta and cook until cooked halfway through, about 3 minutes. Drain pasta, rinse with cold water, and set aside.
Heat remaining butter in a 4-qt. saucepan over medium heat.
Add flour and cook, whisking constantly, for 1 minute. Still whisking constantly, slowly drizzle in milk and cook until sauce has thickened and coats the back of a spoon, 10–15 minutes.
Remove pan from heat. Stir in graviera or kefalotyri cheese, Greek Yogurt Tzatziki, cinnamon, and nutmeg and season with salt and pepper; set béchamel sauce aside.
Heat oven to 350°. Heat oil in a 5-qt. pot over medium heat.
Add shallots and cook, stirring often, until soft, 3–4 minutes.
Add spinach and scallions and cook, covered, stirring occasionally, until wilted, about 3 minutes.
Stir in the reserved béchamel sauce, the dill, and the reserved pasta and transfer mixture to a 9″ x 13″ baking dish.
Sprinkle evenly with reserved bread crumbs and the feta.
Bake until golden brown and bubbly, about 30 minutes. Let cool for 10 minutes before serving.
