1/2 cup vegetable shortening, such as Crisco
1/2 cup sugar
1 1/2 teaspoons vanilla extract
1 large egg yolk
1 1/2 cups all-purpose flour
1/2 teaspoon baking powder
1/4 teaspoon salt
3 tablespoons milk
1 ounce (1 square) unsweetened baking chocolate, melted
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.