* (2 cups loosely packed) Children will love these-they are fun to make and to eat. Adults will also find them irresistible. Preheat oven to 375�. In large bowl, with mixer at low speed, beat egg yolks and milk until well blended. Add flour, sugar, butter, vanilla and salt; beat ingredients until just mixed. Increase speed to medium and beat 2 minutes, occasionally scraping bowl. Divide dough in half. On floured pastry cloth, with lightly floured stockinettecovered rolling pin, roll one dough 0. 13 cm thick. With 6 cm fluted-edged cookie cutter, cut dough into rounds; with 1 cm round cutter, cut out centers from half of rounds. Reserve the dough scraps. Using a pancake turner, place rounds 1 cm apart on ungreased cookie sheets; bake at 375� 8-10 minutes until lightly browned. With pancake turner, remove cookies to wire racks to cool completely. Repeat cutting and baking with second half of dough, rerolling scraps. Prepare frosting: In the bowl of an electric mixer, place all frosting ingredients (except food color) and beat at low speed for 2 minutes. Scrape sides of bowl and continue beating at high speed for 6 minutes. Divide frosting into thirds and tint with food color. On bottom side of cookie without a hole, spread teaspoonful of either green, pink or yellow frosting; top with a cookie with a hole in it to make a "sandwich." Repeat with remaining cookies and frosting. (Use any leftover frosting for graham crackers or cupcakes.) Yield: about 42 sandwich cookies. Larry Rosenberg, author of Muffins & Cupcakes (published by The American Cooking Guild), Fairview, NJ. Randy Shearer