Preheat oven to 400°F (200°C). Line a rimmed baking sheet with parchment, set aside.
Cut acorn squash in halves. Rub halves with 1 tablespoon (15 mL) of the oil and season with a bit of salt and pepper. Place cut side down on baking sheet and bake until tender but not mushy, about 35-40 minutes.
Meanwhile, prepare the filling: heat remaining tablespoon (15 mL) of oil in a large nonstick skillet over medium. Add sausage and cook, stirring constantly, until starting to brown, 3-5 minutes. Scrape into a bowl and place skillet back on heat.
Cook onion, celery and red pepper until onion is fully softened, about 7-10 minutes. Add garlic, thyme, onion powder, paprika and salt and cook, stirring constantly for one minute. Turn off heat.
Add sausage crumbles and spinach to the pan and stir until spinach is wilted, 1-2 minutes. Add apple and stir through. Set aside.
When squash is ready, remove from oven and turn cut side up. Stuff halves with sausage mixture. Turn oven to high broil.
In a small bowl, combine crumbs, nutritional yeast, salt and garlic powder. Sprinkle over the stuffed squash halves and place until the broiler - watch closely! - until crumbs are golden brown, about 1 minute.
