Mix the butter with powdered sugar and add the egg yolks. Season with vanilla. Mix the biscuits and candied fruit. Pour them in the butter and mix. You can use vanilla biscuits, flavored honey and butter or cocoa. I added one crushed gingerbread and 1 package candy M & M (ground). Gradually start adding flour. You do not need an accurate measure your hands alone will feel when the dough is ready. Must remain soft, but not sticky. Work fast, do not knead long arms. Otherwise the water in the butter will begin to separate from the dough and will become brittle and hard. Keep it in the refrigerator for 30 minutes. Roll out the dough into small pieces on the board, lightly dusted with flour or on baking paper. Cut out cookies with cookie cutters. Arrange the cookies on a tray covered with baking paper. Bake them in a preheated 170C oven until slightly pinkish.