Heat olive oil in a large pot over medium heat.
Add diced onion and sauté until translucent.
Stir in minced garlic and cook for another minute.
Add diced tomatoes, including juice, and mix well.
Pour in chicken broth and bring to a simmer.
Add shredded chicken, chili powder, cumin, salt, and pepper.
Let the mixture simmer for 15 minutes to blend flavors.
Reduce heat, then stir in heavy cream until well combined.
Allow the soup to heat through without boiling.
Serve hot, garnished with tortilla strips and diced avocado.