6Edible food colours (Red,orange, yellow, green, indigo and purple)
In a table top mixer, or by hand in a large bowl, mix the icing sugar and butter until combined, add the vanilla, salt and the eggs one at the time.
Once the eggs are combined add the flour a little at thetime, mix until a dough is formed.
Divide the dough into six equal parts, it should be approximately, 380gm each part.
Dye the dough with food coloring by placing a¼ teaspoon of dye on the ball of dough and kneading it until it is one solidcolor. Gloves optional but suggested. You can add more color as desired. Do thiswith a different color for all portions of dough.
Wrap the dough separately in plastic film andrefrigerate, for at least 1 hour before using.
Once the dough rested, take the dough out of the fridge and roll eachportion of dough on waxed paper into a 9x5-inch rectangle.
Freeze for 10 minutes. Lightly brush top of 1 rectangle with milk. Top with another colored dough. Remove waxed paper; brush top with milk. Repeat with remaining dough, alternating colors to make 6 layers. Press together lightly. Wrap dough.
Refrigerate for several hours or overnight. Unwrap dough; cut into 1/4-inch slices. Place 2 inches apart on ungreased baking sheets.
Bake at 350° for 8-10 minutes. Cool for 1-2 minutes beforeremoving from pans to wire racks to cool completely.