Preheat oven to 375°F and line two baking sheets with parchment paper. Place cubed day-old bread in a large mixing bowl. Heat 4 tablespoons butter in a medium skillet over medium heat. Add diced onion and celery, cooking for 5-7 minutes until softened. Add minced garlic and cook 1 minute more. Transfer sautéed vegetables to the bowl with bread. Add chopped turkey, fresh cranberries, dried cranberries, parsley, sage, thyme, rosemary, salt, pepper, and nutmeg. Toss to combine. Pour 2 cups of broth over the mixture gradually, mixing gently. Let sit for 5 minutes, then add remaining broth if needed. The mixture should be moist but not soggy. Pour beaten eggs over the mixture and mix thoroughly with your hands until everything is well combined and holds together. Form mixture into 2-inch balls (about golf ball size), packing them firmly. Place on prepared baking sheets, spacing 1 inch apart. Brush each ball lightly with melted butter for extra crispiness (optional). Bake for 20-25 minutes, rotating pans halfway through, until golden brown and internal temperature reaches 165°F. Remove from oven and let rest 5-10 minutes before serving. Serve warm with gravy or cranberry sauce for dipping.