Heat the oven: Preheat to 400°F (200°C).
Line a baking sheet with parchment for easy cleanup.
Prep the squash: Slice each acorn squash in half from stem to tip. Scoop out the seeds. Brush the cut sides with 1 tablespoon olive oil and sprinkle with a pinch of salt and pepper.
Place cut side down on the baking sheet.
Roast the squash: Bake for 30–40 minutes, until the flesh is fork-tender and lightly caramelized at the edges. Timing varies by size; check at 30 minutes.
Cook the rice: While the squash roasts, bring the vegetable broth to a boil in a medium pot. Add the rinsed wild rice, reduce to a simmer, cover, and cook for 40–45 minutes, or until the grains split and are tender with a slight chew.
If liquid remains, drain; if dry, splash in a tablespoon or two of water near the end.
Sauté aromatics: In a large skillet, warm the remaining 1 tablespoon olive oil over medium heat. Add onion, celery, and carrot with a pinch of salt. Cook 6–8 minutes, stirring, until softened and translucent.
Stir in garlic for 30 seconds until fragrant.
Season the base: Add thyme, sage, black pepper, and cinnamon (if using). Cook 1 minute to bloom the spices.
Combine the filling: Fold the cooked wild rice into the skillet. Stir in dried cranberries, toasted nuts, parsley, lemon juice, and butter if using.
Taste and adjust with salt, acid, and herbs until it pops.
Stuff and bake briefly: Flip the roasted squash halves cut side up. Season the interiors with a pinch of salt. Spoon the rice mixture into each cavity, mounding slightly.
Return to the oven for 8–10 minutes to warm through and meld flavors.
Finish and serve: Top with crumbled feta or goat cheese if you like, or a light drizzle of maple syrup for contrast. Serve hot.