In a large bowl, combine ground turkey, ground sausage, egg, breadcrumbs, Parmesan cheese, garlic, parsley, Italian seasoning, salt, and pepper. Gently toss with hands until all ingredients are evenly distributed.
Roll the mixture into tablespoon-size meatballs and transfer to a large plate.
In a large skillet, heat olive oil over medium high heat. Add half of the meatballs and cook for 4 to 5 minutes until browned on all sides, turning occasionally. They don’t have to be cooked all the way through because they will finish cooking in the soup. Transfer cooked meatballs to a plate lined with paper towels. Repeat the process with remaining meatballs.
In a large pot, heat 1 tablespoon of olive oil over medium high heat. Add onion, carrots, and celery, and cook for 5 minutes, or until veggies have softened. Add garlic and cook for one more minute.
Poor in the broth and bring to a boil. Season soup with Italian seasoning, salt, and pepper, to taste. Add in the pasta and meatballs, reduce the heat to low.
Cover the pot with a lid and cook for about 10 minutes or until pasta is tender and meatballs are cooked through.
Stir in spinach, lemon juice, and crushed red pepper flakes. Cook for one more minute. Remove from heat.
Ladle the soup into bowls and garnish with freshly grated Parmesan cheese, if desired. Enjoy!
