Ingredients

• 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

Instructions

1. Cream the shortening and sugar in a large bowl with an electric mixer. Add the vanilla, and egg yolk and mix well.
2. Sift the flour into a separate bowl with the baking powder and salt. Add the flour mixture and milk alternately to the shortening mixture, beginning and ending with the flour mixture, and mix to form a dough. Divide the dough into 2 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.
3. Unwrap and roll each half of dough between 2 pieces of waxed paper. Roll to a 1/8-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.
4. The next day, preheat the oven to 375 degrees F.
5. Cut the roll into 1/4-inch slices (see Cook's Note) and place about 1/2 inch apart on ungreased baking sheets. Bake for about 12 minutes. Do not brown. Remove carefully with a pancake turner and cool on racks.