Step 1

Preheat the oven to 350 degrees F. Spray a 9-by-13-inch glass baking dish with cooking spray.

Step 2

Bring a large pot of salted water to boil and cook the egg noodles until al dente according to package instructions. Drain the noodles, drizzle with 1 tablespoon of the olive oil and set aside in a large bowl.

Step 3

Heat the remaining 2 tablespoons olive oil in a large skillet over medium heat. Add the onion and scallion whites and cook, stirring occasionally, until translucent and softened, about 7 minutes.

Step 4

Add the garlic to the skillet and cook, cooking frequently, until softened, about 2 minutes. Mix in the scallion greens and spinach and cook until spinach is warmed through, about 3 minutes. Season with 2 teaspoons salt and several grinds of pepper. Pour into the bowl with the cooked noodles and gently mix to incorporate the spinach mixture.

Step 5

Mix the eggs, cream, sour cream, 2 cups of the feta, dill, parsley, nutmeg, 1 teaspoon salt and several grinds of pepper in a medium bowl. Pour into the bowl with the noodles and gently mix until evenly incorporated. Transfer the noodle mixture to the prepared baking dish and sprinkle the top with the Parmesan and remaining 1 cup feta. Bake, rotating halfway through, until the top is golden brown and the custard is set, about 45 minutes. Let cool for 10 minutes before serving.