01 - Preheat oven to 425°F. Arrange red bell peppers on a baking sheet and roast for 20 to 25 minutes, turning occasionally, until skins are blistered and charred.
02 - Place roasted peppers in a bowl, cover with plastic wrap, and let steam for 10 minutes. Peel off skins, discard seeds, and roughly chop the flesh.
03 - Heat olive oil in a large pot over medium heat. Add chopped onion, sliced carrot, and minced garlic; sauté for 5 to 6 minutes until softened.
04 - Add roasted peppers, diced tomatoes with juices, smoked paprika, dried thyme, salt, and pepper to the pot. Cook for 5 minutes, stirring occasionally.
05 - Pour in vegetable broth, bring to a boil, then reduce heat and simmer uncovered for 15 minutes.
06 - Remove pot from heat and purée the mixture until smooth using an immersion blender or a countertop blender in batches.
07 - Stir in heavy cream and warm the soup gently over low heat for 2 to 3 minutes without boiling. Adjust seasoning as needed.
08 - Ladle the soup into bowls and garnish with fresh basil leaves and croutons if desired. Serve hot.