Melt 2 Tablespoons of butter in a skillet over medium heat. Add the squash and onions to the pan. Saute for 5 to 7 minutes, until vegetables are tender.

Remove squash and onions from the skillet and set aside in a large mixing bowl.

Return the pan to the burner, over medium heat, and melt 1 Tablespoon of butter. Add mushrooms to the pan and sprinkle with garlic powder and onion powder. Sauté for 5 minutes, until soft and brown.

In a measuring cup, combine flour, half the broth, salt and pepper. Stir until well smooth and pour over the mushroom mixture. Add the remaining chicken broth and bring to a boil.

Cook for 2 minutes, whisking or stirring constantly, to avoid clumping, until the mixture has thickened.

Reduce the heat to low and add the half-and-half. Stir to fully incorporate. Simmer for 10-15 minutes, stirring frequently to ensure the soup mixture remains smooth and creamy.

Remove the mushroom soup mixture from the heat and set aside to cool slightly.

Grease an oblong, shallow, 2-quart baking dish with butter or cooking spray. Preheat oven to 350 degrees.

Add herbed stuffing mixture and 4 Tablespoons of melted butter to the bowl with the squash and onion mixture. Stir until the stuffing mixture is moistened

Finally, add in the homemade cream of mushroom soup and stir until fully incorporated.

Spread the squash, stuffing and soup mixture into the baking dish. Bake for 30 to 40 minutes at 350 degrees, until heated through but not dried out.