In a large Dutch oven, heat olive oil over medium high-heat. Add apples, onion, carrots, celery, ginger, salt and pepper. Cover and cook, stirring often, for 15 minutes, until apples have broken down and vegetables are starting to brown.
Add broth, increase heat to high, and bring to a boil. Reduce heat to medium-low to maintain a simmer and cook, stirring occasionally, for 20 minutes, until vegetables are soft. Puree mixture with an immersion blender. Stir in Apple cider vinegar.
Make the maple yogurt: Whisk together yogurt and syrup. Drizzle on top of soup and serve.