Prehat oven to 200 degrees C
Drizzle olive oil into large roasting pan. Add onion, carrots, garlic cloves, and a pinch of salt. Toss until coated in oil. Place pumpkin halves flesh side up on the chopped vegetables. Sprinkle pumpkin with additional salt.
Meanwhile melt the butter in a pan until slightly brown - Remove from heat, add sage leaves and stir (careful it will splatter a little) - set aside
Roast in preheated oven until pumpkin is tender and easily pierced with the tip of a knife, about 1 hour. Allow vegetables to cool a bit.
Scoop out pumpkin flesh and place in roasting pan with roasted chopped vegetables. Transfer mixture into large stock pot. Stir in chicken stock, maple syrup and sage butter.
Place pot over high heat and bring to a simmer. Reduce heat to low and slowly simmer to blend flavors, 45 to 60 minutes. Remove from heat.
Blend until very smooth with an immersion blender, 3 or 4 minutes and pass mixture through a sieve.
If soup seems too thick, add a few tablespoons of chicken stock. Stir in apple cider vinegar, a pinch of salt (or to taste), and cayenne pepper.
Garnish servings of soup with a dollop of creme fraiche, chopped chives and toasted pepitas.
