All the yumminess of pizza served as a soup
In a large soup pot over medium heat add the olive oil, onion, mushrooms, red pepper, kosher salt, pepper, and crushed red pepper flakes. Cook 5-8 minutes, stirring occasionally.
Add the spinach and garlic, cook 5 more minutes.
Add the Italian sausage and cook 5 more minutes, breaking up the sausage as it cooks.
Add the mini pepperoni, beef broth, pizza sauce, and Italian seasoning. Bring this to a boil and reduce heat to simmer for 30 minutes, stirring occasionally. Taste for seasoning and add kosher salt, pepper, and crushed red pepper flakes to taste.
Serve with shredded mozzarella cheese on top.