Preheat the oven to 220°C. Line two large baking sheets with parchment paper. Bring the 480 ml vegetable broth to a boil in a medium saucepan, add the wild rice blend, reduce to a gentle simmer, cover, and cook for 40 minutes or until tender.

Place the acorn squash halves cut side up on one baking sheet. Brush them with 15 ml olive oil and season with 2 g salt and 1 g black pepper. Roast for 35 to 40 minutes until the flesh is tender and lightly caramelized at the edges.

While the rice and squash cook, heat 15 ml olive oil in a large skillet over medium heat. Add the chopped mushrooms, onion, and celery. Cook for 8 to 10 minutes, stirring often, until the vegetables soften and the mushrooms release and reabsorb their moisture. Stir in 2 minced garlic cloves and half of the chopped rosemary, and cook for 1 minute more.

Remove the skillet from the heat and stir in the cooked wild rice, dried cranberries, chopped pecans, 1 g salt, and 1 g black pepper. Mix until evenly combined. Taste and adjust seasoning if needed.

On the second baking sheet, toss the Brussels sprouts and carrots with 15 ml olive oil, the maple syrup, 2 g salt, 1 g black pepper, and the remaining chopped rosemary. Spread them in a single layer. Roast for 25 minutes, stirring once halfway through, until browned and tender.

Place the potatoes in a large pot and cover with cold water. Add a generous pinch of salt, bring to a boil, then simmer for 15 to 18 minutes until very tender. Drain well, return to the pot, and let the steam evaporate for 1 minute.

Mash the potatoes with the warmed oat milk, 45 ml olive oil, and 1 minced garlic clove until smooth. Season with the remaining salt and pepper to taste. Cover to keep warm.

When the squash is tender, fill each half generously with the wild rice mixture. Return the stuffed squash to the oven for 10 minutes so the filling heats through and the top lightly toasts.

For the gravy, heat any remaining oil from the measured amount in a small saucepan over medium heat. Add the remaining minced garlic and cook for 30 seconds. Whisk in the flour and cook for 1 minute. Slowly whisk in 360 ml vegetable broth, then add the thyme leaves. Simmer for 3 to 5 minutes, whisking often, until thickened.

Serve the stuffed acorn squash halves on a large platter with the roasted Brussels sprouts and carrots alongside. Spoon the mashed potatoes into a serving bowl and pour the warm mushroom gravy into a small pitcher or bowl for serving at the table.