In a large mixing bowl, cream together the butter and sugar until light and fluffy. Mix in the egg yolk, vanilla extract and almond extract until well blended. Stir in the flour. Divide the dough in half. Roll each half into a log shape about 3 inches in diameter. Wrap in plastic wrap and refrigerate for at least three hours.
Preheat oven to 375 degrees F (190 degrees C). Remove dough from refrigerator and cut 1/8-inch thick slices and place on cookie sheets about 2 inches apart.
Bake for about 10 minutes, or until cookies get a tinge of color. Let cool on wire rack.