1) Preheat the oven to 350°F. Spray a loaf pan with non-stick cooking spray.
2) Heat olive oil over medium heat. Sauté the celery, garlic and onion for about 5 minutes until slightly translucent and aromatic.
3) Stir in the cremini mushrooms and cook for 3 more minutes.
4) Add in the seasonings. Stir to combine.
5) Add the cubed bread to the vegetables. Stir to combine and pour in the vegetable broth. Stir well until the broth is mixed throughout. Remove from heat.
6) Combine the meatloaf and stuffing in a large bowl. Mix well with your hands. Taste and add more salt and pepper if necessary.
7) Spread the mixture into a loaf pan and bake for 25 minutes.
8) Remove from the oven and let stand 10 minutes. Slice and serve with gravy!
For the Gravy:
1) In a saucepan on high heat, whisk the yeast and the flour together. Whisk in the soy sauce and garlic powder and continue until smooth.
2) Slowly pour in the broth. Whisk constantly until smooth.
3) Reduce the heat and simmer 3-5 minutes.
4) Season with salt and pepper to taste.