In a large pot, cook ground beef over medium heat until browned. Drain excess fat.
Add diced onion and garlic to the pot and cook until softened.
Stir in beef broth, diced potatoes, basil, parsley, salt, and black pepper. Bring to a boil, then reduce heat and simmer for about 15-20 minutes, or until potatoes are tender.
In a small bowl, whisk together flour and heavy cream (if using) until smooth. Gradually stir into the soup.
Continue to cook and stir until the soup has thickened, about 5-10 minutes.
Reduce heat to low and stir in shredded cheddar cheese until melted.
If using sour cream or Greek yogurt, stir it into the soup until well combined.
Just before serving, stir in shredded lettuce, diced tomatoes, and chopped pickles (if using).
Taste and adjust seasoning if necessary.
Serve hot, garnished with optional toppings like chopped green onions or crumbled bacon.