buttermilk, egg, and vanilla; mix well. Combine flour, ginger, soda, and salt. Gradually add to creamed mixture, beating just until blended.
Divide dough into six portions. Pat one portion into the bottom of a lightly greased, 9-inch cast-iron skillet. (Chill remaining dough). Bake at 350° for eight to nine minutes. Carefully remove to cooling rack. Repeat with remaining dough, each portion rolled out to size of skillet.
Combine dried apple filling ingredients and cook until soft; mash well. Stack layers, spreading filling between each. Store overnight in refrigerator before serving.
The cook says: As long as my father was living, I cannot remember Christmas without this stack cake.