In a large pot or Dutch oven over medium heat, brown the ground beef until fully cooked. Drain excess fat if necessary.
Add the diced onion and minced garlic to the pot, cooking until the onion is translucent, about 5 minutes.
Stir in the canned diced tomatoes (with juices), beef broth, sliced black olives, and taco seasoning. Bring the mixture to a simmer and let cook for about 10 minutes.
Reduce heat to low and add the cream cheese, stirring until completely melted and incorporated into the soup.
Once the cream cheese is mixed in, stir in the shredded cheddar cheese until melted and the soup is creamy.
Taste and adjust seasoning with salt and pepper, if needed.
Serve hot, garnished with shredded lettuce, diced avocado, and a dollop of sour cream if desired.