Mix the following ingredients thoroughly: 1/4 cup butter or margarine, 1 egg yolk, 1/2 cup sugar, 1 tsp vanilla, 1/4 cup cocoa and 1/2 cup finely chopped nuts or flaked coconut.
Heat oven to 350. Mix flour and salt. Cut in butter. Sprinkle with water and vanilla. Mix well with fork. Using 1/2 of dough at a time, roll out 1/16″ thick on cloth-covered board generously sprinkled with sugar. Cut in 2 1/2″ squares. Spread 1 level tsp filling in center of each square. Bring corners to center. Seal together. Place sealed side up or down on ungreased baking sheet. Bake 15 to 20 minutes. Makes about 2 1/2 dozen.