Heat olive oil in a large pot or Dutch oven over medium heat.
Add the chopped onion and cook for about 5 minutes until soft and translucent.
Stir in garlic and sun-dried tomatoes; cook for 1–2 minutes until fragrant.
Pour in chicken broth and add basil, oregano, red pepper flakes, salt, and pepper.
Bring to a gentle simmer, cover, and cook for 20 minutes to develop flavor.
Reduce heat to low and stir in heavy cream and Parmesan cheese. Stir until melted and smooth. Do not boil.
For a smoother Creamy Tuscan Parmesan Soup, blend partially with an immersion blender if desired.
Garnish with fresh parsley and serve hot.