Adjust oven rack to upper-middle position and heat oven to 475 degrees. Melt butter in a 12 inch oven-safe skillet over medium-high heat. Cook onion and celery until soft, about 4 minutes.
Stir in flour and cook until lightly browned, about 1 minute. Slowly whisk in the broth, gravy and cream and simmer until thickened, 5 to 7 minutes. Add the peas and carrots mix and turkey and cook until heated through, about 2 minutes.
Meanwhile, combine stuffing and egg in large bowl. Place stuffing mixture between pieces of parchment paper and roll into 11-inch circle. Remove top layer of parchment and cut into 6 wedges. Arrange wedges evenly over filling and bake until stuffing is golden brown and crisp, about 12 minutes. Serve.