Preheat oven to 400 degrees F. Spray pan with non stick spray, set aside.
In a large bowl mix the corn muffin mixes, eggs, milk, sage and thyme together. Pour into 8x8 pan and bake for 18-20 minutes until done. Allow to cool while you saute vegetables.
In a large pan or pot over medium heat add butter, onions, celery, garlic, mushrooms and rest of seasonings into a pan to saute until tender. Turn to low heat.
Add broth and bread cubes and fold together. Turn heat off. Break apart cornbread in 8x8 pan and gently fold into the vegetable mixture just enough to combine and pour everything into 9x13" pan. Spread out and reduce heat to 375F. and bake for 20 minutes until lightly brown on top. Serve immediately.