Step 1Cut the squash in half lengthwise, remove the seeds and brush the insides with 2 teaspoons of olive oil. Season with the salt and pepper. Place the squash cut side down on an ungreased baking sheet and roast in a 400-degree oven until tender, about 55 minutes. When the squash is done, cool and scoop the pulp out of the skin. Set aside.
Step 2Meanwhile, heat the apple juice in a medium saucepan. Add the diced apples and poach until tender, about 4 to 5 minutes. Strain the apples from the juices, setting aside the apples to use later. Continue to boil the juice rapidly until it is reduced to 2 cups, about 15 minutes; set aside.
Step 3In a heavy, 5-quart saucepan, heat the remaining 2 tablespoons of olive oil. Add the garlic, carrots, celery and onion and saute until the vegetables are tender, about 10 minutes.
Step 4Add the ginger, lemon grass, bay leaf, thyme, curry powder and rice. Cook, stirring constantly, over high heat for 2 to 3 minutes, until the mixture is fragrant and the spices coat the vegetables.
Step 5Add the chicken stock, heavy cream, reduced apple juice and squash pulp. Stir to combine. Bring the mixture to a boil, then reduce to a simmer. Cover, and cook until the flavors are blended, about 30 minutes.
Step 6Remove and discard the bay leaf. Working in batches and using a blender, carefully puree the mixture or use a stick blender and puree the soup in the stock pot.
Step 7Spoon the soup into bowls and garnish each with a swirl of yogurt, a sprinkling of cilantro and a spoonful of diced apples.