Preheat oven to 450°F (230°C). Sift flour, baking powder, baking soda and salt into large bowl; mix well. Cut in butter with pastry blender or 2 knives until mixture resembles coarse crumbs. Add buttermilk and mustard; mix just until dough comes together. (Do not over mix.) Mix in Cheddar cheese using clean hands, just until blended.