Cube up your white bread as big or small as you like, and add it to a sheet tray and bake at 350° F for about 20 minutes, tossing halfway through. They should be about as crispy as croutons.
In a large skillet, over medium heat, crumble and cook the vegan sausage until browned, about 6-7 minutes. Remove from pan and set aside, don't clean out the pan.
Add the vegan butter and once melted, add in the celery and shallots, cooking until slightly softened about 5-6 minutes. Add in the sage and thyme, stir to combine and cook for about 2 minutes. Then add in the garlic, stir to combine and cook for one minute. Taste and adjust for seasoning. Remove from heat.
In a large bowl, add the dried bread cubes and then fold in the sage and sausage mixture. Add in the veggie broth and fold in, then add in the non-dairy milk and vegan egg and fold in. Lastly, add in the parsley and stir to combine.
Grease a 9x13 inch casserole dish or 12" cast iron skillet with vegan butter, then add in the stuffing and spread evenly. Bake at 350° F for 30 - 40 minutes. I recommend checking around the 20 minute mark, if the top is getting browned too quickly, you can lightly cover with foil. If it looks good, just check it every 5-10 minutes to make sure it doesn't get burned.
Feel free to broil it for a few minutes for deeper browning on top.
Once done, let it cool for a bit and then ENJOY!