In a bowl, combine the herbs, onion, garlic, and egg. Add the heavy cream and panko and mix to combine to allow the panko to absorb the milk.
Add the chicken to the mixture and season liberally with salt, pepper, and crushed red pepper. Use your hands to gently mix together. Do not over mix the chicken.
Roll into tablespoon sized meatballs and transfer to a plate. Set aside in the refrigerator until needed.
Prepare the Aromatics:
Heat the oil in a wide pot over medium heat. Once hot, add the diced onion and sliced celery and cook for 4-5 minutes until they begin to soften. Add the mushrooms and cook for 7-8 minutes until beginning to turn golden brown. Season all over with salt and pepper.
Cook the Broth:
Pour in the chicken stock and the cannellini beans. Bring to a boil and season to your preferences with salt, pepper, and crushed red pepper. You can also add dry thyme if you're not using fresh thyme in your herbs.
Cook the Meatballs:
Carefully add the meatballs to the broth. Bring to a boil, cover, reduce heat and simmer for 15-20 minutes or until the meatballs are cooked through.
Finish the Broth:
Pour in the heavy cream (if using), minced herbs, and arugula. Cook for 5-6 minutes or until the arugula is wilted. Turn off the heat.
To Serve:
Ladle the broth and meatballs into bowls and drizzle with extra virgin olive oil, if desired. Enjoy!