Heat the one tablespoon of butter in a large pot or Dutch oven over medium heat. Sear mushrooms until they begin to brown, but not yet release any liquid — about three or four minutes. Remove them from pan and set aside
Add the second tablespoon of butter. Add the carrots, onions, thyme into the pan and cook for 10 minutes, stirring occasionally, until the onions are lightly browned. Add the garlic and cook for one more minute.
Add tamari, bay leaf, red wine to the pot. Stir in the tomato paste and the broth. Add mushrooms back with any juices that have collected, salt and black pepper to taste and once the liquid has boiled, reduce the temperature so it simmers for 20 minutes, or until mushrooms are very tender.
Combine 1 tablespoon butter and gluten-free flour; stir into the stew. Lower the heat and simmer for 10 more minutes. If the sauce is too thin, boil it down to reduce to the right consistency. Season to taste.
Mushroom Bacon Topping
Preheat oven to 350 degrees
Place mushrooms in a large bowl; drizzle with olive oil and season with salt
Evenly spread mushrooms in a single layer in a shallow glass baking dish. Transfer to oven and bake, tossing with tongs every 5 to 10 minutes, until dry and crisp, taking care not to burn. Remove from baking dish; mushroom "bacon" may be used hot or at room temperature.