Heat the olive oil in a large Dutch oven or soup pot over medium heat.
Add the ground turkey. Cook for 5 to 6 minutes, breaking the turkey apart with a wooden spoon, until browned.
Add the turkey pepperoni, onion, green bell pepper, and mushrooms. Cook for 5 minutes, stirring occasionally, until the vegetables begin to soften.
Add the garlic and tomato paste. Cook for 1 minute, stirring constantly.
Add the crushed tomatoes, diced tomatoes, chicken broth, Italian seasoning, oregano, garlic powder, crushed red pepper flakes, salt, and black pepper. Stir in the cannellini beans.
Bring the soup to a boil. Reduce the heat to low. Simmer uncovered for 15 minutes.
Add the mozzarella and Parmesan cheeses. Stir until the cheeses melt into the soup.
Remove the soup from the heat.
Stir in the fresh basil.
Notes
Tips and Tricks
Drain the turkey if needed - If the cooked turkey releases a noticeable amount of grease, carefully drain it before adding the vegetables.Cut the pepperoni into small pieces - Smaller pieces spread the pizza flavor throughout the entire pot.Adjust the consistency - Add a small amount of chicken broth if the soup becomes thicker than preferred.Add cheese gradually - Stir in the cheese a little at a time so it melts evenly into the hot soup.
Storing and Reheating
Refrigerate - Cool the soup completely and store it in an airtight container in the refrigerator for up to 4 days.Freeze - Place the cooled soup in freezer-safe containers and freeze for up to 3 months. Leave a little room at the top for expansion.Reheat on the stovetop - Place the soup in a saucepan and warm over medium-low heat, stirring occasionally. Add a splash of broth if it has thickened.Reheat in the microwave - Place one serving in a microwave-safe bowl. Cover loosely and heat in short intervals, stirring between each interval, until hot.