Mushroom and Caramelized Onion Thanksgiving Stuffing

My coworkers and I did an early Thanksgiving feast together at work this week so I got to create a stuffing recipe, which turned into a test run of what I will be making for my family's Thanksgiving dinner! I realize "stuffing" is supposed to be "stuffed" into a bird and this is actually a "dressing" recipe, but this is what I'm calling it and I know you know what I mean!

1 loaf french bread
1/2 stick + 1 Tbs unsalted butter
1/2 yellow onion, diced
1/2 yellow onion, thinly sliced
1 c celery, chopped
1 c chopped mushrooms
2 cloves garlic, chopped
3 c low sodium vegetable broth
1/2 tsp dried sage
1/2 tsp dried thyme
1/2 tsp dried basil
1 tsp rosemary
1 1/2 tsp salt
1/2 tsp black pepper
1/4 tsp sugar

1. Cut bread into half-inch cubes and set out on a baking sheet for at least 24 hours to get stale. I got about 10 cups of cubes.
2. Heat 1/2 stick butter on medium heat and add diced onion and celery. Cook for about 5 minutes, until veggies are soft.
3. Add mushrooms and garlic.
4. Add vegetable broth and bring to a boil. 
5. Add sage, thyme, basil, rosemary, salt, and pepper. Stir to combine and cook for 2 more minutes.
6. Put bread into a large mixing bowl.
7. Ladle broth mixture over bread and stir, gradually making sure that all bread cubes are absorbing the mixture.
8. Melt 1 Tbs of butter in pan over medium heat.
9. Add sliced onions and stir.
10. After 10 minutes, add salt and a little sugar to help with caramelization.
11. Continue to cook over medium heat for about 20 minutes, or longer, until onions are a rich brown color. If onions are sticking to pan, add a little water.
12. Add caramelized onions to bread mixture and stir.
13. Pour bread mixture into baking dish.
14. Bake at 350 degrees from 25 minutes.