Preheat oven to 400 degrees F. Line a baking sheet with parchment paper, set aside.
Place squash onto the baking sheet, skin side down. Drizzle 2 tbsp of olive oil, 1/2 tsp salt, and 1/4 tsp pepper. Place into the oven and bake for 45-60 minutes until squash is cooked though and fork pierces through easily. Set aside for 10 minutes to let cool. Once it's slightly cooled down, scoop out the flesh and discard the skin.
Heat olive oil in a large stock pot or Dutch oven over medium heat. Add onion, carrots, and garlic. Sauté the until soft, about 5-6 mins.
Add cooked squash, 1 tsp salt, 1/4 tsp pepper, pinch of cinnamon, and chicken broth. Stir until well combined. Bring to a gentle boil. Place lid on top and simmer for 15 minutes on low heat.
Remove pot from heat. Use an immersion blender and blend until creamy. Or transfer soup into a regular blender and blend until creamy, may need to be done in 2-3 separate batches. Stir in cream until well incorporated.
Line a baking sheet with parchment paper. Assemble baguette slices onto baking sheet. Sprinkle cheddar cheese onto baguette slices. Top each slice with a piece of bacon. Bake for 8-12 minutes, until cheese is melted and bacon is cooked.
Serve butternut squash soup warm with cheddar bacon crostini, garnished with chives.