Chicken Artichoke Stuffed Mushrooms

Combine chicken, broth, and two cups of water in a medium sauce pan. Season with ¾ teaspoon salt and add more water if needed, until chicken is just submerged. Bring to a boil, then reduce to a simmer. Simmer until just cooked through, about 5 minutes. Using tongs, remove chicken to a plate. Let cool slightly. Shred chicken with two forks. Preheat oven to 425° with a rack in the upper and lower third. Line two rimmed baking sheets with parchment paper.  In a large bowl, stir together cream cheese, ¾ cup shredded mozzarella, Parmesan, garlic, Worcestershire sauce, oregano, paprika, and red pepper flakes until smooth. Fold in artichokes, shredded chicken, and green onions. Season with salt and pepper.  Stuff mushrooms with cream cheese mixture and transfer to prepared baking sheets. Top with remaining ¾ cup mozzarella. Bake until mushrooms are cooked, mixture is warmed through, and cheese is melty and golden, rotating trays halfway through, about 20 minutes.  Let cool slightly. Serve warm topped with more green onions and serve.