BAKE the focaccia bread the night before according to the directions provided on the back of Simple Mills Focaccia & Sandwich Bread mix bag.
PREHEAT oven to 350°F.
CUT the loaf of Simple Mills focaccia bread into small cubes.
SPREAD cubes on a large baking sheet to toast in the preheated oven for 25 minutes. This will draw out all of the moisture. (1 loaf of bread will yield approx 5 cups of bread cubes)
While the bread is toasting, HEAT a large sauce pan over medium heat and melt butter.
ADD onions, celery, garlic, shallots, mushrooms, salt, pepper, cloves, and herbs de provence and mix well to combine.
SAUTÉ over low-med heat until vegetables are tender and beginning to caramelize, about 10 minutes.
ADD in 3 tbsp of broth and scrape up any brown bits in the pan, mixing well. Add additional salt for flavor if needed. Remove from heat and set aside.
Once bread is finished baking, REMOVE from oven and transfer to a large glass bowl.
POUR mushroom, onion and celery mixture over the bread and mix well. Once well combined, pour 2.5 cups of bone broth over entire mixture again, stirring again to combine all ingredients.
In a glass baking pan, USE a very small amount of olive oil or butter to grease the pan to prevent sticking. Pour entire mixture, including excess liquid, into glass baking pan.
BAKE for 40 minutes. Stuffing should look browned an crispy on top. Allow to sit for 10 minutes before serving!