Melt 3 Tbsp of butter to a dutch oven or wide soup pot over medium heat. Add shallots and carrots and saute 3 minutes. Stir in garlic and saute 1 minute more. Pour in the broth and the wine and bring to a boil. Reduce heat and cover.
Add remainder of butter to another large pot over medium heat and then add mushrooms. Saute for 10 minutes, stirring occasionally, until the mushrooms are a deep brown but still have some bite to their texture. Sprinkle a dash of salt over them and set aside.
While the mushrooms are cooking, add seitan chunks, thyme, and rosemary to the bourguignon pot and cover, simmering for 20 minutes.
Add mushrooms and their juices to the pot and bring heat up to medium, simmering without a cover. In 5 minutes, check the sauce thickness--if it is too thin, push the meat and veg to the side and quickly whisk in some flour to the broth mixture. Stir into the mixture thoroughly. You want a sauce that will coat the back of a spoon but is still somewhat brothy.
Simmer this on low for another 5 minutes and then check the flavor. If it needs more salt, or broth, add some now.
Use a ladle to serve over mashed cauliflower or potatoes, making sure to add plenty of sauce to the plates. Top with fresh parsley.
Notes
This recipe makes enough for two LARGE portions, or two regular portions with leftovers for the next day.