Place flour and sugar in a stand mixer. Cut cold butter into dry ingredients. Press hard-boiled egg yolks through a fine sieve on top of the dry ingredients. Add raw egg yolks on top. Mix quickly, so that butter does not get mushy. If it appears too dry, add a tablespoon of cream. Chill thoroughly, ideally overnight. No need to grease cookie sheets - plenty of butter in the dough. Start with 1/3 of the dough - roll it out between sheets of wax paper with as little flour as possible, about 1/8th inch think. Cut out simple shapes, a circle or heart, and place on a cookie sheet. Quickly mix remaining dough and chill again, if needed, before rolling the rest. Take a thimble or a smaller cookie cutter and cut a hole in the middle of 1/2 of the cookies. Bake at 350 degrees until the edges just begin to color, 12-15 minutes. Remove from sheets very carefully - they are fragile. Take the bottoms - those without holes - and spread with seedless raspberry or apricot jam. Take the tops - those with the holes- and dip in powered sugar. Put tops on bottoms. Eat all irregulars immediately!