2 small spaghetti squash (or 1 medium), makes around 3 cups cooked squash
1 whole head of garlic
1 cup sliced white button or portobello mushrooms
2 Tbsp olive oil + 1 tsp for garlic
1 tsp dried thyme
1/2 cup tomato sauce
1/2 tsp salt
1/2 tsp pepper
3 large eggs, whisked
Preheat the oven to 375 degrees F., line a baking sheet with foil and grease with oil or cooking spray.
Cut the spaghetti squash in half lengthwise, scoop out the seeds and place the squash cut-side down on a baking sheet.
To prepare the garlic, slice the top off of the entire head and place the garlic, cut side up, in a large piece of foil. Drizzle the garlic with olive oil and sprinkle with salt. Wrap the foil tightly around the garlic and place it on the baking sheet with the squash.
Bake the squash and garlic for 1 hour, until the skin of the squash is fork tender.
While the squash is baking, prepare the mushrooms. Heat the remaining olive oil in a frying pan over medium-high heat, then add the mushrooms. Cook the mushrooms until beginning to brown, stirring occasionally, for around 5 minutes. Add the dried thyme and a sprinkle of salt and pepper then cook for 2-3 more minutes and remove the pan from the stove. Slightly cool the mushroom.
Remove the squash from the oven, carefully scoop out the flesh and place it in a mixing bowl. Save the skin of the spaghetti squash to use for baking the casserole. Stir in the mushrooms, tomato sauce, salt and pepper. Unwrap the garlic from the foil and squeeze all of the roasted soft garlic into the squash mixture. Stir to combine.
Add the whisked eggs and mix everything together until you can no longer see the eggs.
Add the squash mixture to the spaghetti squash skins on the baking sheet. You can also use an 8×8 casserole dish prepared with cooking spray for this.
Bake uncovered for 1 hour in the oven, until the top of the casserole has formed a crust that looks like cheese and is brown around the edges. Let rest for 10 minutes before serving.