1. In a large pot over medium heat, cook the ground beef until browned and cooked through. Drain any excess fat from the pot.

2. Toss in the sliced mushrooms, chopped onion, and minced garlic. Sauté until the mushrooms are tender and the vegetables are fragrant.

3. Pour in the fire-roasted diced tomatoes and beef broth. Stir in the steak seasoning, salt, garlic powder, and black pepper. Allow the soup to simmer for 15-20 minutes, allowing the flavors to meld.

4. While the soup is simmering, toast the mini burger buns and spread them with a generous amount of mayonnaise.

5. Ladle the steaming Bacon Mushroom Swiss Cheeseburger Soup into bowls, and top with chopped cooked bacon and shredded Swiss cheese. Serve the toasted mayonnaise-spread buns alongside the soup for the ultimate cheeseburger experience in a bowl.