Preheat the oven to 350°F. For the sweet potato puree, several times with a fork and place them on a baking tray. Transfer the baking tray to the oven and bake the sweet potatoes at 350°F for 50 minutes. Let the sweet potatoes cool, then peel them, mash them into a smooth puree, and season them with salt.
While the sweet potatoes are baking, prepare the spinach by letting it thaw, squeezing out any excess liquid, and seasoning it with salt & pepper.
For the ground turkey, sauté the chopped onion and minced garlic in vegetable oil, then add in the mushrooms and fry them until golden brown. Remove the mushrooms from the heat and let them cool. Stir together the breadcrumbs and milk until combined.
Stir together the ground turkey, 2 eggs, ketchup, Worcestershire sauce, salt & pepper until combined, then add in the mushroom and bread crumb mixtures.
Place a large piece of plastic wrap on a clean work surface and press 1 cup of the ground turkey mixture onto its surface in an ovular shape. Spoon 2 tablespoons of sweet potato puree and some spinach in the center of the ground turkey.
Cover the layer of spinach with 2 more tablespoons of sweet potato puree and cover the vegetable filling with 1 cup of the ground turkey mixture. Wrap everything up in plastic wrap and mold it so that it resembles a turkey breast. Transfer the ground turkey breast to the freezer and freeze for 1 hour.
Form, fill, and shape the drumsticks using the same technique as you did for the turkey breast, but use slightly less of the ground turkey mixture for each one (about ¾ cup). Transfer the drumsticks to the freezer and freeze for 1 hour.
Use the remainder of the ground turkey mixture to make 2 large and 2 small ovular rolls for the wings. Transfer the wings to the freezer and freeze for at least 30 minutes.
Preheat the oven to 350°F and whisk 1 egg for the egg wash. Remove the plastic wrap from the frozen turkey breast and brush egg wash over it so that the puff pastry will stick to it effectively. Roll out 1 puff pastry sheet and place the turkey breast on top, then cover it with a second puff pastry sheet. Press the dough together firmly, fold the edges of the puff pastry sheet under the turkey breast, and cut off any excess dough. Transfer the puff pastry-wrapped turkey breast to the center of a baking tray lined with parchment paper.
Repeat the same technique with the drumsticks, but only use 1 puff pastry sheet per drumstick. Transfer the puff pastry-wrapped drumsticks to the baking tray and position them near the base of the turkey breast.
Cut 2 long triangles out of the puff pastry sheet for the wings. Place the larger ground turkey roll on the wider side of the triangle and the smaller one near the pointed end. Fold up the sides up and seal the wing with a second puff pastry triangle. Repeat this process for the second wing, then position the wings on the baking tray with the rest of the puff pastry-wrapped turkey.
Whisk 2 egg yolks for the egg wash and brush the egg wash over the puff pastry-wrapped turkey. Transfer the baking tray to the oven and bake the puff pastry-wrapped turkey dinner at 350°F for 1 hour.