Grandma Lizzie made these little cookies that looked like they could spin. They’re not only pretty but also delicious. Grandma would always have some sort of sweet treat baking when we arrived for a visit. These pinwheels were as fun to play with as they were to eat.
Cream the shortening and sugar. Add the egg yolk and vanilla. Mix well.
Sift the flour with the baking powder and salt. Add the flour mixture and milk alternately to the shortening mixture, beginning and ending with the flour. Divide the dough into two halves. To one half, add the chocolate, mixing thoroughly. Wrap both sections of dough in separate pieces of plastic wrap and chill in the refrigerator for about 1 hour.
Unwrap and roll each half of dough between 2 pieces of waxed paper. Roll to a ⅛-inch thickness. Remove the waxed paper from the top of each layer of dough. Place the white layer on top of the chocolate layer, and roll up carefully as you would a jellyroll, using the waxed paper to roll smoothly. Wrap the roll with the waxed paper and chill overnight in the refrigerator.
The next day, preheat the oven to 375°F. Cut the roll into ¼-inch slices (see Note) and place about ½ inch apart on an ungreased cookie sheet. Bake for about 12 minutes. Do not brown. Remove carefully with a pancake turner and cool on racks.
When cutting the roll, use a very sharp knife and wipe the blade after each slice to avoid mixing the colors and to keep the cookies round. You could also use an electric knife. To cut the dough with a thread, slide a 12-inch length under the roll, cross it over at the top, and pull right through.