Heat oven to 375°F. Grease cookie sheets with shortening. In large bowl, beat butter, granulated sugar and brown sugar until light and fluffy. Add buttermilk and eggs; beat well. Add flour, baking powder, baking soda, cinnamon, salt, nutmeg and orange peel; blend well. Add oats; mix well. Fold in cranberries and walnuts. Drop by teaspoonfuls onto cookie sheets.