In a small bowl, mix together the Italian seasoning, oregano, garlic powder, fennel seeds, salt, black pepper, and red pepper flakes. Set aside for later use.

Place a large skillet over medium-high heat. Add the oil and swirl to coat. Add the ground turkey and break it up. Sprinkle with the seasoning mix and cook for 3 minutes, then add the onions and continue to cook for another 5-7 minutes or until the turkey is no longer pink and onions soften.

Transfer the turkey mixture to the slow cooker. Add the diced potatoes, sliced mushrooms, and chicken broth; stir gently to combine.

Place the lid on the slow cooker and cook for 6 hours on LOW (or 3 hours on HIGH) or until the potatoes are just tender. Increase the temperature setting to high.

In a small bowl, whisk 2 tablespoons cornstarch into 1 cup half-and-half. Add this mixture to the slow cooker and stir. Replace the lid and allow the soup to cook for 30 minutes.

Remove the lid and stir in 4 cups chopped kale. Replace the lid and cook for another 20-30 minutes, stirring occasionally.

Ladle the soup into bowls and garnish with Parmesan cheese, parsley, and additional red pepper flakes.

Serve warm and enjoy your homemade Zuppa Toscana!