Preheat the oven to 400°F. Cut the spaghetti squash in half and scoop out the seeds. Brush or spray it lightly with oil and sprinkle with salt and pepper. Bake face down on parchment paper for 25-30 minutes, or until soft and shreddable with a fork.
Meanwhile, sauté the veggies and veggie sausage together in the oil until browned.
Shred and fluff the spaghetti squash with two forks.
Top the squash with marinara, the veggies, and sausage.
Garnish with salt, pepper, dried or fresh Italian herbs, and nutritional yeast (optional)