Preheat oven to 375 degrees. Lightly grease baking sheets.
Sift together flour, baking powder and salt. Cream together the butter and sugar. Add the egg yolks and vanilla, beating until light and fluffy. Mix in the dry ingredients.
Shape into 1 inch balls. Push your thumb through center of each ball and shape dough into a ring. Dip top of each ring in decorating candies. Place cookies onto the prepared sheets.
Bake at 375 degrees for 10 to 12 minutes or until golden brown. Remove from the baking sheets and let cool on racks. Makes 2 dozen cookies. Enjoy!