At a bakery they probably use shortening or shortening/margarine combination.
BUTTER TEA COOKIES
1½ lbs. butter or margarine
¾ lb. powdered sugar
4 cups cake flour (16 oz)
2½ tbsp. nonfat dry milk
½ tbsp. salt
½ cup egg whites (approximately 2 egg whites)
3 tbsp. water
½ tbsp. vanilla
Sprinkles, nuts or cherries for decoration
Beat butter with an electric mixer until very light and fluffy. In another bowl, sift together the powdered sugar, 3 cups of the cake flour, dry milk and salt. Add to creamed butter a little at a time. Add egg whites to mixture and beat for 1 minute on medium speed.
Sift remaining 1 cup cake flour and add to mixture. Add water and vanilla to form a soft dough. Scrape down sides of bowl and mix for about 4 minutes additional.
Preheat oven to 350 degrees.
Place dough in a pastry bag fitted with a 1-inch star tip. Press cookies out onto baking sheets lined with parchment paper.
Decorate as desired with sprinkles, nuts or cherries.
Bake 8 to 10 minutes or until lightly browned.