Cream the butter, sugar, and vanilla.
Add the white flour, mix.
Add one cup of the spelt flour, mix.
Add the remaining spelt flour and the egg and mix well.
Roll the dough into a neat rectangle between two sheets of parchment paper until it is ¼ inch thick.
Place into the refrigerator to chill for half an hour. Preheat your oven to 325° F.
Cut the dough into 1½ inch squares and arrange them on an un-greased baking sheet. Chill for fifteen minutes.
Bake for 14-18 minutes.
Cool on the baking sheet for ten minutes and then remove to a wire rack to finish cooling.