In large bowl, cream butter & sugar until light & fluffy . Beat in egg yolks. & vanilla.

In a small bowl, combine flour , salt. Gradually beat into creamed mixture. Mixing well ( dough will be stiff) .

On a well floured surface, roll out dough to 1/8" thickness. With sharp knife or pastry cutter. Cut dough into 2-1/2" squares.

Place 1/2" apart onto ungreased cookie sheet. Sprinkle with colors.

Bake at 375° . For 7-8 min.until lightly browned. ( Watch carefully as cookies will brown Quickly. ) Remove to wire racks to cool. Store.