With a big Christmas cookie cutter (Santa Claus, Christmas tree, sleigh, angel, etc…), Cut the dough in the centre of the square. Leave all the dough in place. With a knife, cut puzzle pieces around the shaped cookie, leaving them on the sheet. Then carefully separate the pieces from each other leaving a 1-cm (1/2-inch) space to prevent them from touching while baking. Lightly brush with milk. Decorate with sprinkles and sugar crystals.