In a large pot, heat the olive oil over medium heat. Add the diced onion, garlic, bell pepper, carrots, and celery. Sauté for about 5-7 minutes until the vegetables are softened.
Add the chicken broth and cubed potatoes to the pot. Stir in the Cajun seasoning, smoked paprika, salt, and pepper. Bring to a boil, then reduce the heat to low and let simmer for 20-25 minutes, or until the potatoes are tender.
Using a potato masher or immersion blender, mash or blend the soup to your desired consistency (smooth or chunky).
Stir in the heavy cream and heat through for an additional 5 minutes. Adjust seasoning as needed.
Serve hot, garnished with sliced green onions and crumbled bacon if desired.