Preheat your oven to 400°F (200°C). Cut the spaghetti squash in half lengthwise and scoop out the seeds. Drizzle with olive oil, season with salt and pepper, and place cut-side down on a baking sheet. Bake for 30-40 minutes until tender.
Stir in spinach and vegetable stock; cook until spinach wilts (2-3 minutes).
Once the squash is roasted, use a fork to scrape strands into the skillet with the shrimp mixture. Drizzle with lemon juice and gently toss everything together.