1. In a large pot, heat the olive oil over medium heat. Add the onions and sauté until they become translucent, about 5 minutes.
2. Add the garlic, red bell pepper, and celery. Continue to cook for another 4 minutes until the vegetables are tender.
3. Sprinkle in the Cajun seasoning, stirring well to coat the vegetables.
4. Add the diced potatoes and chicken broth, bringing the mixture to a boil. Reduce the heat and let it simmer for 20 minutes, or until the potatoes are soft.
5. Using an immersion blender, carefully blend the soup until smooth. Alternatively, transfer the soup in batches to a blender. Be cautious with the hot liquid!
6. Stir in the heavy cream, then season with salt and pepper to taste. Let the soup simmer for an additional 5 minutes.
7. Ladle the soup into bowls and garnish with sliced green onions and chopped parsley.

One tip Mama Lou taught me is to always taste as you go. Cooking is an art of adjustments, and sometimes the best tweaks happen when you trust your palate!