Preheat a large soup pot over medium high heat.
Add olive oil, celery, red pepper flakes, pinch each of salt & pepper.
Sauté until onions are translucent.
Add butternut squash, bay leaves, cinnamon, chicken stock, and another pinch of salt & pepper.
Bring to a simmer, cover, and let cook for 40 minutes.
Once the soup is cooked, remove bay leaves.
Blend until smooth using an immersion blender.
Alternatively, puree soup in a blender, working in batches.
When soup is smooth, stir in cider vinegar and adjust seasonings to taste.
Optional: for a silkier (and more decadent) soup, stir in ½ C heavy cream at the end.
Garnish with fresh dill, if desired.