"The topping crushed-potato chip is so crunchy." Serving: Makes 6 servings

• 1/4 cup (1/2 stick) unsalted butter
• 2 1/2 cups thinly sliced leeks (white and pale green parts only; from about 2 large)
• 1/4 tsp. celery seeds
• Coarse kosher salt
• 1/4 cup all purpose flour
• 2 cups whole milk
• 1/2 cup half and half
• 1 tsp. fresh lemon juice
• 8 oz. wide egg noodles
• 1/2 cup coarsely grated Gruyère cheese (about 2 1/2 oz.)
• 2 tbsps. chopped fresh dill
• 2 5- to 6-oz. cans albacore tuna (preferably packed in olive oil), drained, broken into 1/2-inch chunks
• 2 cups coarsely crushed salted potato chips (about 2 oz.)

• Butter the 8x8x2-inches glass baking dish. In a heavy large saucepan, melt the unsalted butter over medium heat. Add the celery seeds and leeks to the saucepan. Sprinkle them with coarse kosher salt lightly. Cover the saucepan and cook and stir frequently the mixture for 8 minutes until the leeks are tender yet not brown. Add the flour and stir the mixture for 1 minute. Add the half-and-half and milk gradually. Simmer the mixture while frequently stirring it for 5 minutes until slightly thickened. Mix in the lemon juice. Season the mixture with pepper and coarse kosher salt to taste. Remove it from the heat.
• In the meantime, cook the egg noodles in a large pot filled with boiling salted water, stirring occasionally until tender. Let the noodles drain and reserve 3/4 cup of its cooking liquid. Place the noodles into a large bowl. Spread the leek sauce all over the noodles. Add the dill and grated Gruyere cheese. Whisk the mixture until blended. Pour in the reserved cooking liquid by tbsps., about 8 tbsp. until the mixture is creamy and moist. Fold in the tuna. Spread the mixture onto the prepared baking dish. (This can be prepared a day in advance. Just let it cool slightly, and then chill while uncovered until cold. Cover the dish with a foil and keep it refrigerated.)
 • Set the oven to 375°F for preheating. Cover the noodle casserole with a foil and bake it for 20 minutes if freshly made or 30 minutes if it’s from the fridge until heated through. Remove the foil and sprinkle the casserole with the crushed potato chips. Bake while uncovered for 10 more minutes until the filling bubbles and the top is golden brown. Serve while hot.