Preheat oven to 350°F.
Squeeze as much liquid as possible from spinach. Place in greased 8-inch square baking dish. Sprinkle with celery salt and mix well. Top with whole or halved hard cooked eggs.
Toss cheese with corn starch, onion and rosemary. Heat milk in saucepan. Add cheese mixture, a little at a time, stirring after each addition. Simmer 3 minutes. Season to taste with salt and pepper. Pour over eggs; sprinkle with paprika.
Bake for 20 minutes, or until bubbly around the edges. If desired, serve over English muffins.