Add egg yolks, then shape dough and divide into a ball; divide into two parts. Roll each portion between sheets of parchment paper into a rectangle 1/8-inch thick.

Slide rectangles (leave dough between sheets of parchment paper) and refrigerate until firm.

When firm, gently peel off paper. Cut dough into diamonds 3 inches long by 2 inches wide. Arrange 1-inch apart on baking sheets.

To make a meringue topping, beat egg whites until foamy, gradually adding salt, remaining sugar, and vanilla. Spread meringue smoothly and evenly over each diamond.

Bake in a preheated 250°F oven for 30 minutes, or until the meringue is crisp but light in color and bottoms are lightly browned.

Remove from oven and cool on baking sheet for 10 minutes, then finish cooling completely on a wire rack.

Makes about 4 dozen cookies.