Prepare flax "egg" by stirring flaxseed and water together in a small bowl. Let sit at least 10 minutes.
Spread bread cubes out on a baking sheet. Bake until toasted (about 10-15 minutes). Transfer bread to large bowl.
Heat vegan butter in pan on stove at medium heat. Add onion, garlic and celery and sauté until vegetables are soft (about 15 minutes). Add mixture to bowl with bread cubes.
Stir thyme, rosemary, salt, pepper and flax "egg" into bowl.
Slowly add vegetable broth, being careful not to make bread too soggy, and stir. Add 1 cup at a time and let it absorb for a minute before adding more.
Spoon mixture into each spot in the muffin tin, packing it down and filling it slightly above the top. Bake in oven for 18-20 minutes, until edges are browned.
Remove from oven and let sit until cool enough to handle. Add a scoop of cauliflower mash (see above) on top of each muffin and top with gravy.
Recipe by The Colorful Kitchen at https://thecolorfulkitchen.com/2016/11/14/vegan-stuffing-muffins-cauliflower-mash/