Cream butter and sugar together. Blend in eggs, milk, and vanilla. Stir in sifted flour, baking soda, salt, and cream of tartar. Fold in fruit and nuts. Form dough into two 8-inch rolls and roll in coconut, if desired. Wrap dough rolls in waxed paper and refrigerate overnight. When ready to make, cut cookies into 1/4-inch slices and bake at 375 F for 8 minutes.