Preheat oven to 400 degrees. Spread bun cubes in a single layer on a baking sheet. Bake until golden and crispy, about 10-15 minutes; set aside.

Brown the ground beef in a large pot. Drain and set aside.

In the same pot melt 1 TBSP butter. Add onion, garlic, carrots, celery, and Italian seasoning. Saute until onions become translucent, about 2-3 minutes.

Add the broth, potatoes and ground beef and bring to a boil. Reduce heat, cover and simmer 10-12 minutes or until potatoes can be pierced easily with a fork.

Meanwhile, in a small skillet, melt the remaining 3 TBSP butter. Add the flour and cook 3-5 minutes, until it turns the color of peanut butter. Add to the soup and simmer, uncovered, for 5-6 minutes, until the soup has thickened. Reduce heat to low.

Stir in the cheese and milk, and season with salt and pepper. Ladle soup into bowls and top with additional cheese, bun croutons and pickles and tomatoes, if desired. Enjoy!