Spread bread cubes onto 2 sheet pans in a single layer. Toast at 350°F for 10-15 minutes or until crisp and dried all the way through.
Increase oven temperature to 375°F.
Heat olive oil in a large skillet over medium heat. Add diced celery and onions. Cook until starting to soften, about 5-6 minutes.
Add mushrooms, thyme, sage, and garlic. Cook until tender, about 4-5 minutes. Add salt and pepper.
Add low sodium vegetable broth. Fold in bread cubes making sure to coat all the cubes. Season with more salt and pepper, if needed.
Transfer mixture to an oiled 7 ½" x 9 ½" baking dish (or similar size that holds 2.75 quarts). Cover with aluminum foil.
Bake at 375°F for 30 minute. Remove aluminum foil and bake another 10 minutes, or until golden brown.
Notes
You can make this a day or two ahead of time if needed. Just follow all the steps in the recipe, but don't bake it.Cover it and place it in the fridge. Then on Thanksgiving bake it as per instructions.It also tastes great when reheated in the microwave.