Preheat oven to 400ºF if using raw turkey breasts.
If using raw turkey breasts, place them on a baking sheet and season with salt, pepper, poultry seasoning and a drizzle of EVOO. Roast them in the oven for about 45 minutes, or until a thermometer placed in the thickest part of the breast registers 165°F. Loosely cover with foil to keep warm and reserve.
While the turkey is roasting, make the stuffing: Toast the bread slices then spread with the softened butter, about 1/2 tablespoon per slice. Chop into one-inch cubes and reserve.