In a large bowl, beat butter until creamy. Add the 1 1/2 cups of sugar, the salt and vanilla and beat until light and fluffy. Beat in egg yolks. Add flour and mix thoroughly to make a stiff dough. In a small bowl, beat egg whites with a fork just until whites are broken up, then beat in the 1/4 cup sugar. Mix cinnamon with nuts. Heat oven to 325°. Take half the dough (about 2 cups) and roll it out on an ungreased baking sheet to 1/2-inch thick rectangle. Cut off edges to make a neat 10X12-inch rectangle. Brush dough with 2 tablespoons of the egg white mixture; sprinkle with 1/4 cup of the nut mixture. Bake in the lower third of the oven for 15 to 18 minutes, until lightly colored. Remove from the oven and cut into 30 squares. Let cookies cool 2 minutes before transferring to a wire rack to cool. Roll out and bake remaining dough the same way, then gather both sets of trimmings and roll them out too. Makes 90 cookies. Store in an airtight container at room temperature or freezer.