Thaw broccoli and drain any excess water.

Preheat oven to 350°F (175°C).

Finely chop onions.

Sauté the chopped onions in butter until softened.

In a separate bowl, beat the eggs.

Add the beaten eggs to the sautéed onions and stir to combine.

In a large mixing bowl, combine the drained broccoli, flour, and 1/2 cup of bread crumbs.

Add the Cheez Whiz to the broccoli mixture and mix well.

Pour the egg and onion mixture into the broccoli mixture and stir to combine thoroughly.

Pour the casserole mixture into a baking pan.

Sprinkle the remaining 1/2 cup of bread crumbs evenly over the top of the casserole.

Bake in the preheated oven for 30 minutes, or until golden brown and bubbly.