Preheat oven to 350°F (175°C).

Chop the onion into small pieces.

Melt 1/4 cup of margarine in a skillet.

Sauté the chopped onion in the melted margarine until it becomes tender and translucent.

In a large mixing bowl, combine the sautéed onion, cream of mushroom soup, drained chopped mushrooms, Cheez Whiz, garlic powder, chopped parsley, salt, pepper, slivered almonds, and partially cooked and drained frozen chopped broccoli.

Mix all ingredients thoroughly until well combined.

Spoon the broccoli mixture into a 2-quart casserole dish.

Sprinkle the herb-seasoned stuffing mix evenly over the top of the casserole.

Drizzle the remaining 1/4 cup of melted margarine over the stuffing mix.

Bake in the preheated oven for 30-40 minutes, or until golden brown and bubbly.