Heat olive oil in a large stockpot.
Cut bacon into small pieces and cook them in the oil for 4-5 minutes until crispy.
Dice carrots, celery, and onions and add them to the stockpot.
Cook for another 5 minutes on medium heat.
Rinse beans under cool water and add them to the pot.
Add chicken broth and fresh rosemary sprigs.
Bring to a boil, reduce to a simmer for 40 minutes.
Remove the rosemary sprigs, and blend the soup with an emersion blender. If you do not have an emersion blender, add soup to a stander blender and mix until creamy.
Stir in half n half and serve.