Preheat the oven to 350 degrees.
In a large skillet combine turkey, vegetables, soup, milk and seasonings. (If you are using fresh vegetables, you can cook them in a tablespoon of butter over medium heat for about 10 minutes before adding the turkey, soup and seasonings.)
Heat the turkey mixture over medium heat until it comes to a light boil. Simmer for about 10 minutes.
Pour into an ungreased 9 by 13-inch baking dish and spread the mixture out evenly in the dish.
For the topping, combine the flour, baking powder and salt in a bowl. Cut the butter into pieces, then cut into mixture with a fork or pastry blender until mixture is crumbly.
Stir in the buttermilk. Gather the dough into a ball, then break it into chunks. Spread the chunks out over the turkey mixture in the casserole dish.
If you prefer, you may roll the dough out into a rectangle and lay it on top of the mixture. If you do this, poke the dough all over with the tines of a fork.
Bake in the oven for about 30 minutes, until the crust is browned.