Avocado slices and/or fried egg for serving (optional)
Heat a large soup pot or Dutch oven over medium heat and brown sausage, breaking it up into small pieces with a spatula. If your sausage generates too much grease to your liking, drain it a little bit.
Add onion and garlic. Sauté until fragrant, about 2-3 minutes.
Add mushrooms and bell peppers, followed by dried oregano and Italian seasonings. Combine well.
Add crushed tomatoes and beef bone broth into the saucepan, followed by pepperoni slices. Stir to combine. Turn the heat up to high and bring to a boil, then simmer for 15-20 minutes.
Ladle into serving bowls and top with mozzarella and parmesan cheeses. Optionally, serve with avocado slices and fried eggs. Enjoy!
Slow Cooker Version:
Brown sausage over medium-high heat in a nonstick skillet.
Drain the grease from the sausage and place the meat in a slow cooker.
Add all the other ingredients (except the cheese and toppings) to the slow cooker.
Cover and cook on low for 6-8 hours.
Dish and serve with cheese, avocado slices, or even fried eggs if desired.