Gather and prepare all the ingredients. Chop the onion, mince the garlic, shred or dice the cooked chicken.
Heat olive oil in a large pot over medium heat. Add the chopped onion and sauté until it becomes translucent, then add the minced garlic and cook for an additional minute until fragrant.
Add the cooked chicken to the pot and stir it with the onion and garlic, letting it cook for a few minutes to absorb flavors.
Pour in the crushed tomatoes and chicken broth. Stir well to combine all the ingredients.
Add dried basil and season with salt and pepper to taste. Stir the soup, then bring it to a simmer. Let it cook on low heat for about 15-20 minutes, allowing the flavors to meld together.
For a creamier texture, you can use an immersion blender or transfer a portion of the soup to a blender (in batches if necessary) and blend until smooth. Return the blended soup to the pot.
Stir in the heavy cream, and let the soup simmer for an additional 5-10 minutes, allowing it to thicken slightly. Adjust seasoning if needed.
Ladle the thick and creamy chicken tomato soup into bowls. Garnish with fresh basil or parsley if desired. Serve hot and enjoy!