Heat olive oil in a large skillet over medium-high heat.

Add pumpkin and onion to the skillet.

Cook and stir until lightly browned.

Transfer the pumpkin and onion mixture to a slow cooker.

Pour in enough chicken broth to cover the pumpkin.

Tie rosemary, thyme, sage, cinnamon sticks, and bay leaves into a cheesecloth sachet.

Place the herb sachet into the slow cooker.

Cover and cook on Low for 4 hours.

After 4 hours, remove the herb sachet.

Stir in heavy cream.

Puree the soup with a hand blender until smooth.

Serve immediately.