Lay out the bread overnight on the kitchen counter. You want to dry out the bread. The next day, cut dried bread in 1 in cubes to make the breadcrumbs.
Melt butter in a large pot over medium heat. Add celery and cook for 5 minutes, or until it's soft.
Next, add the onion to the celery and butter mixture and cook for another 5 minutes, stirring frequently until the onion is soft.
Add salt, pepper, thyme, and garlic powder and stir well.
Then, take your pot off the heat.
Slowly add bread and beaten eggs. We usually add ¼th of the bread and eggs and mix everything together well.
Continue this pattern, adding ¼th of the bread and eggs, until everything is in your pot and mixed very well.
If your stuffing mixture seems dry, add some chicken stock (about 2-3 tbsp at a time) to moisten it up.
After you're all done mixing, add your parmesan cheese and mix once more.
If you're making the stuffing muffins, cook in nonstick muffin tins for 20-25 minutes at 350 degrees.
If you're making stuffing in a pan, cook in a nonstick baking dish for 30 minutes at 350 degrees.