This gluten-free dish is a great stand-in for your classic carby Thanksgiving stuffing.
Preheat the oven to 425°. On a baking sheet, toss the carrots with 2 tbsp. oil and the rosemary; season with salt and pepper and spread out in an even layer. Roast until tender, 25 to 30 minutes.
Meanwhile, in a medium saucepan with a lid, bring the stock to a boil. Add the rice and bay leaves; season with salt. Bring back to a boil; reduce heat to medium-low. Cover and simmer until the rice is tender, about 25 minutes. Fluff with a fork; discard the bay leaves.
Meanwhile, in a large skillet, heat 1 tbsp. oil over medium. Add the onion; season. Cook, stirring often, until soft, about 5 minutes. Transfer to a bowl; mix in the thyme. In the same skillet, heat the remaining 2 tbsp. oil over medium-high. Add the mushrooms; season. Cook, stirring often, until they begin to brown, about 5 minutes. Add the garlic; stir until the mushrooms are browned, 2 to 3 minutes longer.
In a large bowl, mix the carrots, rice, mushroom mixture, and parsley.