In a large pot, heat the olive oil over medium heat. Add the chopped onion, green bell pepper, and celery. Sauté for about 5 minutes until the vegetables are softened.
Stir in the minced garlic and cook for an additional minute until fragrant.
Add the diced potatoes, chicken broth, and Cajun seasoning to the pot. Bring to a boil, then reduce heat and simmer for 20-25 minutes, or until the potatoes are tender.
Once the potatoes are cooked, use a potato masher to mash some of the potatoes in the pot for a thicker consistency, leaving some chunks for texture.
Stir in the heavy cream and season with salt and pepper to taste. Heat through for another 5 minutes.
If using, stir in the crumbled bacon just before serving.
Serve hot, garnished with chopped green onions.