1/2 cup butter
1/2 teaspoon baking powder
1/2 cup sugar
l/8 teaspoon salt
1 egg yolk
3 tablespoons milk
2 teaspoons vanilla
2 squares unsweetened chocolate (2 ounces)
1 3/4 cups sifted flour

Preheat oven to 350°F. Beat butter and add sugar gradually, beating until creamy and light. Beat in egg yolk. Melt chocolate in microwave in a perfectly dry bowl and add to the mixture. Sift flour once before measuring. Sift flour, baking powder and salt together.

Add the flour mixture alternately with milk and vanilla. Form into rolls 3 inches in diameter and chill for several days.

When cookie mixture is firm, cut into 1/8 inch thick slices and bake for 12 to 15 minutes on baking sheet.