Preheat the oven to 425 degrees Fahrenheit. Line a nine-inch round pan.

In a two-quart saucepan, mix milk with cornstarch. Heat milk until it thickens and boils. Cook for one minut, then remove from heat. Cool slightly.

In a large bowl, mix yolks, spinach, cheese, and seasonings. Stir in warm milk.

Beat the six egg whites until peaks form. Gently fold into spinach mixture.

Sprinkle bread crumbs into the baking pan, if using, then pour in the batter. Bake for 30 minutes.