The puff pastry crust isn’t the only secret to the success of this turkey pot pie recipe. As for that filling, we start by roasting a boneless turkey breast, but you could certainly swap it for 1½–2 lb. of frozen vegetables. Have your egg wash ready to gloss the top of the puff pastry sheet as soon as you lay it on the warm filling—this is not the time to wait around. Leaving it too long over the hot filling will allow the butter to melt out, resulting in a dense pastry.