Preheat oven to 350° F (176° C). Lightly grease a 3-Quart Casserole Dish and set aside.
Spread bread cubes onto a baking tray and place in oven until they are dry and slightly toasted. About 15-20 minutes. Move them around occasionally and keep an eye on them so they don't burn. Place the toasted cubes in a large mixing bowl and set aside.
Increase heat to 375 degrees F
In a large pan, add 2 tablespoons of butter over medium heat. Add onion, celery and sauté until softened, about 5-6 minutes. Now add garlic and sauté until fragrant, about 30-60 seconds.
Add remaining 2 tablespoons of butter, once melted, add the mushrooms, dried thyme, dried rosemary and sage. Sauté for 5-6 minutes until mushrooms are softened.
Add just 2 cups of broth, salt & pepper to the pan. Bring to a simmer and cook for 2-3 minutes to combine flavors.
Remove from heat and slowly add the mixture to the bowl of bread cubes, using a ladle. Then add the fresh parsley and toss gently to combine. Keep adding broth until desired moisture is achieved. The bread should be very moist, but not soggy. Let the bread sit for a minute to determine if it needs more broth. Make sure all of the liquid is absorbed into the bread. If more moisture is needed after the pan is emptied, just add plain vegetable broth to the bowl. Taste for seasoning and add more as needed.
Place mixture into the prepared casserole dish and wrap tightly in foil.
Place in the oven and bake for 25-30 minutes or until heated throughout. Remove foil and bake uncovered for 15-20 minutes or until lightly brown & crispy on top. Let sit 10 minutes before serving. Enjoy!