- Preheat oven to 375 °F.
- Place squash, cut side down, on a baking sheet and cook until tender, about 45 minutes.
- Set aside to cool.
- Scoop out the inside and discard the seeds and strings.
- Saute pine nuts and green onions in oil for 1 minute.
- Add mushrooms, zucchini, yellow squash and tomatoes and saute until just about tender, 5 minutes or so.
- Stir in the remaining ingredients.
- Spoon the vegetable mixture into the squash shells.
- Serve immediately.