To prepare a strawberry rhubarb pie III recipe, you will first need to prepare the ingredients for the pie. Place the sugar, butter, eggs, vanilla, and salt in the mixing bowl. In another bowl, whisk together the flour, baking powder, salt, nutmeg and cinnamon. Pour the dry ingredients into the wet ingredients and stir until combined. Add the buttermilk and mix until the mixture is light and fluffy. Gradually add the milk mixture to the egg mixture, mixing well after each addition. Spoon the batter into pie shells and bake for 20 minutes at 325 degrees F. Remove from the oven and allow to cool for 10 minutes before serving.