My partner started making this recipe with my leftover spaghetti squash and it quickly became one of our favorites! It's packed with veggies, but has a rich heartiness that is great for cold winter months.
This recipe came from The Crowded Kitchen. Make sure to check out their site for more details on this and other recipes.
1 medium (~2.5 lb.) spaghetti squash (the amount is flexible, depending on how squash-forward you want your soup)
¼ cup + 1 tablespoon olive oil, divided
1 yellow onion, diced
2-3 cloves of fresh garlic, minced
1 cup diced carrots
1 cup thinly sliced celery
8 cups vegetable broth (or chicken broth)
2 - 14.5 ounce cans diced tomatoes (or similar volume of fresh tomatoes)
2 tablespoons tomato paste
3 tablespoons all purpose flour
1 tablespoon dried Italian seasoning blend
1 teaspoon salt
½ teaspoon ground black pepper
1 tablespoon freshly squeezed lemon juice
4 cups chopped Swiss chard or other leafy green (spinach, arugula, or turnip greens work nicely)
¼ cup chopped fresh parsley
⅓ cup grated parmesan
Preheat oven to 400˚F. Slice the spaghetti squash in half lengthwise, then scoop out the seeds with a spoon.
Brush each half of the spaghetti squash with 1 tablespoon of olive oil and season with some salt and pepper.
Place the squash cut side down on a parchment paper-lined baking sheet, and use a fork to poke some holes in the back of the squash (this helps release steam in the oven).
Roast the squash for 30 minutes or until the squash is fork tender. Remove from the oven, let cool for a few minutes, then flip and use two forks to pull the squash away from the skin.
BONUS TIP: If you scrape the spaghetti squash into a colander, put that colander in a large bowl, season the squash to taste with salt and let sit for an hour and up to overnight, the excess moisture will drip out of the squash so that you have less liquid from the squash. This is less important for soup, but is group when making spaghetti squash with red sauce and you don't want it to be too soupy. You can also use the drained squash liquid as a soup base just like vegetable broth.
While the squash is roasting, add ¼ cup of olive oil to a large pot over medium heat. Once the oil is heated, add the onions and garlic and sauté for 5 minutes, then stir in the carrots and celery and cook for another 5 minutes.
Stir in tomato paste, Italian herbs, salt, and pepper, then stir in the flour and cook for 1-2 minutes.
Add the broth and tomatoes and bring soup to a boil, then reduce heat to low and simmer for 20 minutes.
After 20 minutes, transfer the soup to a heat safe blender, add lemon juice, and blend until smooth.
Pour the soup back into the pot and stir in the Swiss chard, parsley, spaghetti squash “noodles”, and parmesan. Cook for 8-10 minutes on medium low heat just until the greens have wilted.