Plantains, a starchy variety of banana that's a staple food in the tropics, are best served cooked. Omit if unavailable.
Place garlic in a food processor and pulse until finely chopped. Add onion and pulse until finely chopped. Set aside. Place jalapeno in food processor and pulse until finely chopped. Add celery and pulse until finely chopped. Set aside. Place carrots in food processor and pulse until finely chopped.
Heat 1 tablespoon of the olive oil in a medium stockpot over medium heat. Add the garlic and onion and saute, stirring occasionally, until onion is translucent, about 6 minutes. Add jalapeno, celery, and carrots and saute for 5 minutes. Add the squash, chicken stock, bay leaf, curry, turmeric, cayenne, 1 teaspoon of the salt, and pepper to taste, and bring to a boil. Reduce heat and add the plantain. Cook until the vegetables are tender, about 8 minutes.
Meanwhile, in a small saute pan, heat remaining tablespoon of olive oil over medium-high heat. Add pumpkin seeds and remaining 1/2 teaspoon salt and cook for about 30 seconds, shaking pan constantly to prevent burning, until all the seeds have popped. Remove from heat and add parsley.
Place 2 cups of the cooked vegetables and about 1/2 cup of the liquid in the bowl of a food processor and puree until smooth. Stir puree back into the soup. Adjust seasonings, and stir in the creme fraiche, if desired. Garnish with roasted pumpkin seeds.