Preheat oven to 400 degrees F (200 degrees C). Line a baking sheet with parchment paper or aluminum foil.
Place butternut squash, cut-side up, on the prepared baking sheet. Coat the cut sides with olive oil; season with salt and pepper.
Bake in the preheated oven until butternut squash is tender when pierced with a fork, 45 minutes to 1 hour. Remove squash from oven and cool slightly, about 10 minutes.
Scoop flesh from roasted butternut squash and transfer to a saucepan; add broth, garlic powder, onion powder, curry powder, salt, and pepper. Bring squash mixture to a simmer until flavors blend, about 10 minutes.
Pour squash mixture into a blender no more than half full. Cover and hold lid down; pulse a few times before leaving on to blend. Puree in batches until soup is smooth.
Whisk sour cream, lime juice, and lime zest together in a bowl until lime cream is evenly mixed. Serve soup in bowls; top with a dollop of lime cream.
