Sift flour with baking powder and salt. Cut in shortening until mixture is as fine as corn meal. Add milk, mixing until a soft dough is formed. Knead lightly on floured board for about 20 seconds. Roll to about 1/4 inch thickness and spread well with soft butter. Now spread one half of the dough very generously with maple sugar which has been scraped from the pail. Fold the other half of buttered dough over the sugared half. Cut in 1 inch squares and place tightly together in buttered baking pan. Bake quickly in 450 F. for 15 minutes.