Press the Sauté button on the Instant Pot® and melt butter. Add carrots and cook until tender, about 5 minutes. Add apples, onion, garlic, ginger, tarragon, and nutmeg and cook until fragrant, about 2 minutes. Press the Cancel button.
Add broth and stir well. Close lid and set steam release to Sealing, then press the Manual button and adjust cook time to 10 minutes.
When the timer beeps, let pressure release naturally, about 15 minutes. Remove lid and stir well. Use an immersion blender, or work in batches with a blender, to purée soup until smooth. Stir in cream, salt, and pepper. Sprinkle with chives and serve hot.