To make the squash:
Preheat oven to 400 degrees F.
Cut spaghetti squash in half the long way.
Scoop out seeds.
Brush with olive oil and season with salt.
Place on baking sheet cut side up.
Bake in preheated oven for 40-50 minutes, until squash is tender and the flesh separates into spaghetti-like strands when pierced with a fork.
While squash is cooking, make the lentil curry.
To make the lentil curry:
In large soup pot, heat olive oil over medium heat.
Add onion, celery and carrots, and cook until softened, about 10 minutes.
Add garlic and cook another minute.
Add curry powder, cumin, coriander, salt, lentils, and broth, and stir well to combine.
Bring to a boil and let simmer for 10 minutes.
Add coconut milk and garbanzo beans and simmer another 10 minutes, until lentils are tender.
Stir in spinach until wilted.
Ladle into roasted spaghetti squash or soup bowls.
Top with plain yogurt and cilantro.